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FEBRUARY 1981 Vol. 6, No. 2 
$2.50 in USA/$2.95 in Canada 

A McGraw-Hill Publication 




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BYTE February 1981 




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Q 



Cromemco 

incorporated 

280 BERNARDO AVE., MOUNTAIN VIEW, CA 94043 • (415) 964-7400 

Tomorrow's computers today 



In The Queue 



Volume 6, Number 2 



February 1981 



Features 

36 An Extremely Low-Cost Computer Voice 
Response System by James C Anderson / infinite clip- 
ping produces acceptable computer speech. 

44 A Computer-Controlled Tank by Steve 

Garcia / A wireless remote-control link to a personal com- 
puter enhances Milton-Bradley's Big Trak. 

68 A Beginner's Guide to Spectral Analysis, 
Part T by Mark Zimmermann / A nonmathematical treat- 
ment of Fourier transforms. 

106 A Pascal Library Unit for the Mlcromodem 

II by Thomas H Woteki / Pascal routines which allow the 
Apple to perform mass-transfer and processing of files via the 
Micromodem II. 

142 Dynamic Memory: Making an Intelligent 

Decision by Larry Malakoff / Dynamic memory boards 
can have one-sixth the power and half the space of static 
types, but these advantages are useless if the board doesn't 
work. 

152 Stacking Strings In FORTH by John 

Cassady / A set of "words" for the FORTH vocabulary adds 
string-handling capabilities to the language. 

1 64 Articulate Automata by Kathryn Fons and 

Tim Gargagliano I A look at the physiology of speech and 
at how the electronic equivalent of the human vocal tract (the 
voice synthesizer) is programmed. 

220 Image Processing With a Printer by Clark A 

Calkins / With this simple system a little hardware goes a 
long way in processing and printing images. 

312 A/D and D/A Conversion — An Inexpensive 
Approach by Roger W Mikel / This fast converter 
requires a minimum of parts and supplies 8 bits of resolution 
over a 5 V range. 



318 Turn Your COSMAC VIP into a Frequency 
Counter by Andrew Modla / Display frequencies in the 
range of I to 1 1 ,004 Hz on your COSMAC computer. 

326 A Heating and Cooling Management 
System by Tom Hall / How to build a remote temperature 
sensor. 

332 Modifying the SwTPC Computer by Thomas 
J Weaver / Modifying the SwTPC 6800 computer to accept 
either the 6800 or 6809 processor board. 

Reviews 

30 Radio Shack's Daisy Wheel Printer II 
by Yvon Kolya 

96 Infinite BASIC and Infinite Business 
by Scott Mitchell 

202 IRV, a TRS-80 Utility Program by Teri Li 
253 The Heath H-I4 Printer by Bradford Rehm 
262 Zork, The Great Underground Empire 
by Bob Liddil 

Nucleus 

6 Editorial: Computer Speech: An Update 

1 6 Letters 

92, 266, 271, 325 Programming Quickies 

94, 102, 290, 309 BYTE'S Bits 

138, 188, 196, Technical Forum: Recording with Current: 

Nonlinearities in Illumination: Build a Null Modem 

212 BYTELINES 

274 Education Forum: Microcomputers in the Chemistry 

Lab 

280 Ask BYTE 

288 System Notes 

289 Software Received 
292 Books Received 

294 Clubs and Newsletters 

298 Event Queue 

304 Book Reviews 

324 Cartoon 

336 What's New? 

382 Unclassified Ads 

383 BOMB, BOMB Results 

384 Reader Service 



BYTE 






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Page 30 



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Page 164 



Page 220 



February 19S1 © BYTE Publications Inc 3 



M 



Editor in Chief 
Christopher Morgan 

Technical Editors 

Richard S Shuford; Gregg Williams: 

Curtis P Feigel; Harold Nelson; 

Stan Miastkowski; Kevin Cohan; Bruce Roberts; 

Charles Freiberg, New Products; Steve Ciarcia, 

Mark Dahmke, Consulting Editors 

Copy Editors 

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Warren Williamson; Robin M Moss; 
Anthony J Lockwood 

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Karen A Cilley; Jon Swanson 



Production 

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Dealer Sales 

Marketing 

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Laura Hanson 



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Asst Controller; Karen Burgess: Jeanne Cilley 

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Publishers 



Virginia Londoner; Gordon R Williamson; 
John E Hayes, Associate Publisher: 
Cheryl A Hurd. Publisher's Assistant 



Officers of McGraw-Hill Publications Com- 
pany: Paul F McPherson, President: Executive 
Vice Presidents: James E Boddorf, Gene W 
Simpson; Group Vice President: Daniel A 
McMillan: Senior Vice President-Editorial: Ralph 
R Schulz; Vice Presidents: Kemp Anderson, 
Business Systems Development; Stephen C 
Croft, Manufacturing; Robert B Doll, Circulation; 
James E Hackett, Controller; William H Ham- 
mond, Communications: Eric B Herr, Planning 
and Development; John W Patten, Sales; 
Edward E Schirmer, International. 

Officers of the Corporation. Harold W 
McGraw Jr. President, Chief Executive Officer 
and Chairman of the Board: Robert F Landes, 
Senior Vice President and Secretary: Ralph J 
Webb, Treasurer. 




In This Issue 

This month we talk about voices — computer voices, that is — and several 
other topics as well. 

Consulting Editor Mark Dahmke speaks out on speech in the editorial 
"Computer Speech: An Update." We also have two theme articles: "An 
Extremely Low-Cost Computer Voice Response System," which shows how 
to computerize your vox humana for very little money, and "Articulate 
Automata," which looks at the physiology of speech. 

Also in this issue is Steve Ciarcia's do-it-yourself computerized Big Trak; 
everything you've always wanted to know about dynamic memory; inexpen- 
sive A/D and D/A conversion; and much more, including reviews of the new 
Radio Shack Daisy Wheel Printer II, the Heath H-14 printer, not to mention 
Zork and IRV. 



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February 1981 © BYTE Publications Inc 





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Computer Speech: An Update 



Guest Editorial by Mark C Dahmke 



In 1972 I saw an advertisement in Scientific American for the Votrax speech 
synthesizer — a multiple-board system that produced fairly intelligible speech. 
Although digital speech synthesis has been with us for more than a generation, 
it wasn't until the early seventies that relatively low cost, compact synthesizers 
were available for use in industry. At the time, I became very interested in the 
concept and wanted to experiment with a synthesizer, but the price was still 
too high for my budget. 

Finally, in August 1976, BYTE published an issue on speech synthesis. The 
article "Friends, Humans, Countryrobots: Lend me your Ears" described in 
detail the Computalker CT-1 speech synthesizer designed by Computalker 




Photo 1: The author of this month's guest editorial, Mark Dahmke (left), 
demonstrating the special speech-generating computer system, "The Bionic Voice," he 
developed for his friend Bill Rush. The Computalker -based system allows Bill, a quadri- 
plegic, to "speak" with the aid of a head stick. Mark and Bill were the subjects of a 
feature story in Life magazine last year that was later condensed in the Reader's Digest. 
Hollywood is interested, too: a movie is being produced for television that will tell their 
story and show how personal computers can make a profound difference in people's 
lives. Mark is a Consulting Editor for BYTE, and has had a continuing interest in com- 
puter speech for many years. His forthcoming book, Microcomputer Operating 
Systems, will be published by BYTE Books later this year. ...CM (Photo courtesy Brian 
Lanker). 



February 1981 © BYTE Publications lnc 



Circle 4 on inquiry card. 



TRS-80* Model I Computer Owners . . . 




Double-density storage. 
It's really here! 



Here at Percom. And your authorized Percom dealers. 

And double-density storage is here in a big way. Because now 
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And get the storage that precisely meets your application 
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Not to mention the service and quality that's made Percom the 
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Although rated for double-density operation, all 
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You can operate these drives in ordinary single- 
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Or, you can add a Percom DOUBLER™ to your 
Tandy Expansion Interface and store data and 
programs in either single- or double-density 
format. 



Under double-density operation, you can store 
as much as 350 Kbytes of formatted data — de- 
pending on the drive model — on one side of a 
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Available in 1-, 2- and 3-drive configurations in 
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TFD-100™ Drives 

TFD-100 drives are "flippy" drives. You store twice 
the data per minidiskette by using both sides of the 
disk. TFD-100 drives store 180 Kbytes (double- 
density) or 102 Kbytes (single-density) per side. 
Under double-density operation, you can store a 70- 
page document on one minidiskette. 



TFD-200™ Drives 

TFD-200 drives store 350 Kbytes (double-density) or 
197 Kbytes (single-density) on one side of a minidis- 
kette. By comparison, 3740-formatted eight-inch 
disks store only 256 Kbytes. Enormous on-line stor- 
age capacity in a 5" drive, plus proven Percom 
reliability. That's what you get in a TFD-200. 




_ The DOUBLER™ — This proprietary 
adapter for the TRS-80* Model I com- 
puter packs approximately twice the 
data on a disk track. 



Depending on the type of drive, you 
can store up to four times as much 
data — 350 Kbytes — on one side of a 
minidiskette as you can store using a 
Tandy standard Model I computer drive. 

Easy to install, the DOUBLER merely plugs into the disk 
controller chip socket of your Expansion Interface. No rewir- 
ing. No trace cutting. 

And because the DOUBLER reads, writes and formats 
either single- or double-density disks, you can continue to 
run all of your single-density software, then switch to dou- 
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Included with the PC card adapter is a TRSDOS*- 
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Each DOUBLER also includes an on-card high- 
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The DOUBLER works with standard 35-, 40-, 77- and 
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Note. Opening the Expansion Interface to install the 
DOUBLER may void Tandy's limited 90-day warranty. 

Free software patch This software patch, called PATCH PAK™, 
upgrades TRSDOS* for operation with improved 40- and 77- 
track drives. For single-density operation only. 



Quality Percom products are available at authorized dealers. Call toll free 
1-800-527-1592 for the address of your nearest dealer or to order directly from 
Percom. In Canada call 519-824-7041. 

tv , , „ "■"„ „ . ■;.- - :■ Prices and specifications subject to change without notice, 

trademark of Percom Data Company, Inc. 

trademark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company 



PEflCCM 



PEHCOWI DATA COMPANY. INC. 

211 N. KIHBY • GABLANDTX • 75042 
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Editorial _^_^^_^-^^^^^_ 

Consultants of Santa Monica, California. The CT-1 was 
an S-100 board, consisting of a formant-based syn- 
thesizer, driven by nine parallel output ports. The data 
rate required was only 100 bytes per control parameter 
per second, or 800 bytes per second for normal speech. 

Several software packages were provided: the 
CTMON program and later CTEDIT, allowing the user 
to enter and edit parameter data. Another package called 
CSRl, the Computalker Synthesis by Rule Program, ac- 
cepted as input a character string of phonemes from the 
International Phonetic Alphabet and generated fairly 
good speech. During the mid-1970s, several other single- 
board speech synthesizers became available, allowing 
hobbyists and researchers to experiment with state-of- 
the-art hardware and software without going into debt. 

It was not until early in 1979 that I obtained a Compu- 
talker board for experimentation. The project was to de- 
sign a "Bionic Voice" for my friend Bill Rush, a student at 
the University of Nebraska who has cerebral palsy. (See 
my article, "A Voice for Bill," in the Winter 1979 issue of 
onComputing.) I used the CSRl package and wrote a dic- 
tionary handler program to make the system easy to use 
(since Bill does not have full control of his limbs, he types 
hunt-and-peck style using a stick attached to a band 
around his forehead). 

More recently, I attended a VOCA (Voice Output 
Communication Aid) Conference in Berkeley, California, 
in May 1980. It is obvious from such conferences and 
discussions that voice output for the nonvocal and non- 
verbal (and talking terminals for the blind) are high on 
the list of potential applications of voice input/ output 
technology. 

On the consumer electronics front, VIO (voice in- 
put/output) technology seems to be the trend setter of 
the eighties. This becomes immediately apparent when 
one walks through a consumer electronics show, the 
West Coast Computer Faire, or numerous other product 
shows. Instead of just flashing lights and color video 
displays, products are now talking at, about, and with 
you. 

Some recent developments in speech synthesis include 
the Votrax SC01 single-chip formant synthesizer men- 
tioned in "Articulate Automata" in this issue. Texas 
Instruments has been at the forefront of the LPC (linear 
predictive coding) approach. One of its most successful 
products, Speak & Spell, shows what can be done in the 
consumer products market. 



Articles Policy 

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8 February 1981 © BYTE Publications Inc 



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Editorial 

As VIO technology has become more readily available, 
there is a natural tendency to make everything from 
washing machines to automobiles talk back. Although 
the concept is a novel one, I have enough noise pollution 
to contend with without adding anonymous electronic 
voices. The real problem with voice output is that it is 
omnidirectional. If you're surrounded with devices that 
spontaneously vocalize, it's not always easy to determine 
where the voice came from. Picture the executive who 
has three or four telephones on his desk all ringing 
simultaneously, all sounding the same. Just as high-den- 
sity video displays can cause sensory overload, multiple- 
voice-output devices can also overload the aural channel 
to the brain. 

Voice recognition has taken longer to develop because 
of the many differences between speakers and the dif- 
ferent shades of nuance inherent in contextual informa- 
tion. Factors such as the emotional content of the 
speaker's voice, the accent or dialect, and (the biggest 
problem) continuous recognition, have slowed the evolu- 
tion of voice input technology. Continuous recognition 
means that the computer must be able to determine the 
beginning of one word and the ending of the last — not a 
trivial project. For example, the machine may have to 
distinguish between "I speak" and "ice peak." The prob- 
lem is further compounded by regional accents and other 
variables. While great strides have been made in this 
area, it will probably be many years before generalized 
continuous voice recognition systems become available. 
Isolated word recognition is a much simpler problem, 
and systems are now available with better than 90 per- 
cent accuracy when working with a limited vocabulary. 

With any new or evolving technology, the challenge is 
to use it effectively, efficiently, and with imagination. 
Voice input/output promises to open a whole new di- 
mension to the man-machine interface, one that can be 
sensed without needing to be seen. 

At the end of my onComputing article, "A Voice for 
Bill," I wrote, "I cannot even begin to imagine what uses 
Bill will find for his new voice. But if past accom- 
plishments are any indication of things to come, I want to 
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10 February 1981 © BYTE Publications Inc 



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• purchase orders & receiving reports 

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■ physical inventory checklists 

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Editorial. 




High 
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* Apple II and The Cashier are trade names of Apple Computer Inc 



/ visited Texas Instruments in early November and was 
given a demonstration of their text-to-speech tech- 
nology. The text-to-speech system uses a TMS5200 
LPC (linear predictive coding) speech-synthesizer 
chip similar to that used in the Speak & Spell product 
line (see photo 2). A message may be entered in stan- 
dard English, represented in ASCII. The text is then 
converted to allophone codes (allophones are subsets 
of a phoneme, the basic unit of speech) which are in 
turn used to retrieve LPC parameters from an 
allophone library stored in ROM (read-only memory). 
Several algorithms are used to smooth the resulting 
parameters and adjust the amplitude and intonation to 
yield continuous-sounding speech. The system has in- 
herent advantages; the allophone tables are quite 
small, typically 3 K bytes for 128 allophones. Other 
languages may be implemented by changing the text- 
to-allophone rules. I experimented with a version of 
text-to-speech that ran on a TI 99/4 personal computer 
development system. It accurately interpreted the 
silent "e" on the end of words like "while" and 
"release" but misinterpreted the (nonsilent) "e" on the 
end of my last name, which is not surprising. When 
given the word "synthesizer" is said "syntheniner." 

TI is also working on a timesharing system that is 
similar to The Source. It will interface with the TI 99/4 
and use its graphics, sound, and voice outputs. The 
system is completely menu driven, and will even log 
on for you. It sends blocks of information to the TI 
99/4, each with a label indicating what kind of data is 
coming. In this way text, graphics, speech, and music 
may be sent independently. If the user's system doesn't 
have certain features, it simply ignores the blocks of 
data it can't handle. If you ask for the weather reports, 
it draws a picture on the screen of a sun, rain clouds, 
or something in between, plays an appropriate tune 
(ie, "Rainy Days and Mondays"), displays text giving 
the temperature and other vital information, and can 
also recite the temperature using text-to-speech. It 
will be interesting to see how the system is received on 
the consumer market.... MCD 



New Computer Speech Developments 

Scott Instruments of Denton, Texas, recently an- 
nounced the VET/2 — a speech-recognition interface for 
the Apple II. It will run with any existing software 
because, once loaded, either keyboard or voice input 
may be used. The program will handle forty-word vocab- 
ularies, with the option of overlaying other vocabularies 
to double or triple the number of words. 

Street Electronics of Anaheim, California, has an- 
nounced the Echo series of speech synthesizers. Versions 
are being designed for the Apple II and the TRS-80. The 
units use the Texas Instruments TMS5200 LPC syn- 
thesizer chip mentioned in the editorial. The software 
driver runs in about 900 bytes of memory. Individual 
vocabulary words take between 10 and 20 bytes, depend- 
ing on the length of the word MCD ■ 



12 February 1981 © BYTE Publications Inc 



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Letters 



Katchlng Up with Khachlyan 

I would like to commend the authors 
of "Khachiyan's Algorithm" (G C 
Berresford, A M Rockett, and ] C 
Stevenson) published in the August and 
September 1980 BYTEs (pages 198 and 
242, respectively). Their presentation il- 
lustrated the essentials of the algorithm 
without getting bogged down in its 
derivation. However, now that I under- 
stand it (I hope), it is somewhat disillu- 
sioning to realize that the "amazing 
shortcut" appears to be only a nonprac- 
tical mathematical curiosity. 

I have some observations regarding 
the algorithm. First, the huge initial 
volume subsequently requires the in- 
credible precision. Hadamard's initial 
volume is much smaller, and this should 
reduce the precision requirements; but 
by how much? Also, if upper bounds 
are defined for all X„ would this be 
helpful7 

Even if the precision problems are 
solved, the total number of arithmetic 
operations to solve a large linear-pro- 
gramming problem still appears to be in- 
tractable. The upper bound for the 
number of iterations is lbLn , and each 



iteration uses Order(« + m) multiplica- 
tions for the matrix inner products. 
Presumably, if a solution exists, the 
number of iterations will be much less 
than ltLn (but by how much?), and the 
number of multiplications per iteration 
can be reduced to Order(n + m) via 
Strassen's algorithm. However, both of 
these appear to be greater than those re- 
quired by the usual revised Simplex 
algorithm. While the Simplex algorithm 
can require Order(2") iterations, it usual- 
ly finds the optimal solution in 
Order(m). Also, each iteration needs 
only Order(mn) multiplications (revised 
Simplex). 

Memory requirements also seem to 
put Khachiyan's algorithm at a disad- 
vantage. The giant A array (see state- 
ment 430, listing 1, September 1980 
BYTE, page 246) can be reduced to 
negligible size using linked lists, and the 
Ql and W arrays could use the same 
space, but this still leaves three (m + ri) 
by [m + n) arrays for Khachiyan's 
algorithm. In contrast, the only large ar- 
ray for the revised Simplex is the m by 
m B array. 

The problem of solving large linear- 
programming problems looks more 



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promising if array-oriented hardware is 
used. For example, a clocked matrix 
multiplier can read in, compute, and 
write out the inner product of two n by 
n matrices in 5 n clock periods. This 
would be an immediate benefit for the 
revised Simplex as well as a help to 
Khachiyan's algorithm, if the precision 
problem can be overcome. 

William J Butler Jr 
44 Dees Cr 
Warwick RI 02889 



Berresford, Rockett, 
and Stevenson Reply 

We are happy that you found our ar- 
ticles on Khachiyan's algorithm so infor- 
mative. Our purpose was to encourage 
such experimentation with the 
algorithm. As the articles explained 
(and, incidentally, earlier than any other 
journal as logged in the February 1980 
issue of Abstracts of Papers Presented to 
the American Mathematical Society,), 
Khachiyan's algorithm is not capable of 
immediate practical application largely 
because of the incredible precision re- 
quired. 

In fairness to Leonid Khachiyan, it is 
clear from his paper that he never in- 
tended his result as a practical method 
for solving linear-programming prob- 
lems. In fact, linear programming is only 
mentioned in one sentence in the intro- 
duction, the rest of the paper being 
devoted to the consistency problem for 
linear inequalities. His purpose was a 
purely theoretical one: to prove that 
linear consistency and, therefore, linear- 
programming problems could be solved 
in polynomial instead of exponential 
time. It was the American and European 
press (with the exception of BYTE) that 
erroneously construed the result as one 
of practical rather than theoretical im- 
portance. (In fact, many other journals 
have had to issue retractions or correc- 
tions of earlier ill-considered statements.) 

As to your specific questions, there is 
little we can say except to answer "yes": 
your suggestions would doubtlessly im- 
prove the algorithm. Dr Philip Wolfe of 
IBM (Yorktown Heights, New York) has 
been serving as a clearinghouse and 
evaluator for the numerous improve- 
ments to the algorithm that have been 
suggested, but none so far seem to ac- 
celerate the algorithm by as much as one 
order of magnitude. Thus, it is far from 
competitive with the revised Simplex 
algorithm. While the Klee-Minty exam- 
ple shows that the Simplex method is an 
exponential-time algorithm, problems 
similar to Klee-Minty rarely occur in 
practice, and when they do, standard 



16 February 1981 © BYTE Publications lnc 



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Letters. 



tricks (such as reseating) usually greatly 
reduce the time needed for solution. In 
fact, experience seems to indicate that 
the revised Simplex method is almost 
linear in the number of variables, thus 
making it hard to beat. 

A more complete answer to your 
questions about improving Khachiyan's 
algorithm will have to await large-scale 
experimentation by IBM and others. 



Comments on the Heath H-89 

In regard to Mark Dahmke's review 
of the H-89 (see "The Heath H-89 Com- 



puter," August 1980 BYTE, page 46), I 
agree with him until he starts talking 
about the "disadvantages." The text 
editor is not that hard to operate, and, if 
he thinks it is, he can get a different one 
from HUG (Heath User's Group) or 
other sources in Buss. He also mentions 
the lack of a RUN "FNAME" command 
in BH (Benton Harbor) BASIC, but, in 
version 1.6, which is the version Mr 
Dahmke worked with, you can say 
CHAIN "FNAME" with the same results. 

All of Mr Dahmke's other observa- 
tions are true, but there are cures. For 
example, to keep the disk head from 
banging up and down, change the HS 



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Save all or part of output on disk 
Switch from specialty printer to CP/M 
list device 

Print the same file on either specialty 

or standard printer 



Version 1 . 1 is now available 

EASE OF OPERATION 

With all its power, the MAGIC WAND is 
remarkably easy to use. This is no acci- 
dent. The command structure is designed 
to be flexible and logical so that you can 
perform basic functions with a minimum of 
commands. 

We have included in the manual a step- 
by-step instructional program, for the per- 
son who has never used a word-proces- 
sor before. The trainee uses sample files 
from the system disk and compares his 
work to simulated screens and printouts. 

In addition to the lessons, the manual 
has a complete documentation of the 
command structure, special notes for pro- 
grammers, an introduction to CP/M for 
non-programmers and a glossary. The 
manual is typeset, rather than typewritten, 
for greater legibility. 

We have written the manual in non- 
technical English, because wewantyou 
to read it. We don't overload you with a 
bunch of jargon that could confuse even a 
PhD in Computer Sciences. 

We send out newsletters so that users 
of the MAGIC WAND can learn special 
applications of the print commands. For 
example, we might show you how to cre- 
ate a mailing list or set up an index for 
a file. 

In short, we've done everything we can 
to make things easy foryou. Because the 
best software in the world is just a bunch 
of code if you can't use it. 



For more information , call or write: 

sttiaYY business o^vcaXvous, uic. 

3220 Louisiana • Suite 205 • Houston, Texas 77006 • 713-528-5158 



CP/M is a registered ii 



k ol Digilai Research Coip 



jumper to open and the HM jumper to 
closed in the disk unit on the "program- 
ming plus." Then the head stays loaded 
as long as the motor stays on, about a 
minute after the last operation. Of 
course, you could time-delay the load 
signal. 

The last, and probably more impor- 
tant, point is how not to need the 
HDOS system on every disk. On ver- 
sion 1.6, the command SET HDOS 
STAND-ALONE can be used and, after 
the warning message, the command 
RESET SY0: will be honored. This might 
mess up versions earlier than 1.6; and, if 
you land on a disk while not in PIP or 
ONECOPY, the SYSCMD.SYS will 
load. If the verions differ, you might get 
a FATAL SYSTEM ERROR, but, all in 
all, it is a good trade-off. Be sure to 
LOAD LP: and other DUDs before 
RESETing after BOOT up. 

Bill Pinkston 
Saltillo MS 38866 



If I may add a few things to Mr 
Dahmke's review of the Heath H-89: 
Heath's BH BASIC is neither fast nor 
high in precision (my Ohio Scientific C3 
will run circles around it), but it does 
have one great advantage for the debug- 
ging phase of programming. While other 
BASICs will null all variable and array 
values upon a revision of any line of 
program, however trivial, BH BASIC 
does not. Thus you can stop execution, 
fix up a defective line, and restart in 
mid-program, rather than having to re- 
run from the beginning — a real advan- 
tage for long programs, and for pro- 
grams requiring many INPUTs to get 
going. 

A detail I like about the H-89 is its 
ability to take commands in lowercase, 
converting input to uppercase as needed. 
That's very nice if you spend a lot of 
time in the word-processing mode. 

Oddly, Mr Dahmke had little to say 
about the display and keyboard. I have 
to cope daily with a Televideo 912, an 
industrial-grade terminal which will 
cause you to appreciate the superior 
quality of the H-89 display and key- 
board. The 912 is susceptible to false 
key contacts, which usually cause the 
display to do truly weird things, thereby 
forcing you to abandon your input and 
to refresh the entire display. It also gives 
no audible confirmation of key contact; 
and the 80-character line is limited to 
perhaps two-thirds of the screen width, 
wasting the rest of the screen. The H-89 
terminal runs at 9600 bps (bits per sec- 
ond) — some have been pushed to 19,200 
bps — a difference especially noticeable in 
word-processing and financial programs, 
for which execution time is limited by 
the display, rather than by computation. 



18 February 19S1 © BYTE Publications Inc 



Circle 14 on inquiry card. 



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supply is primarily for peripherals, without 
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Circle 15 on inquiry card. 



BYTE February 1981 19 



Letters. 



I have to disagree with Mr Dahmke's 
assertion that the Heath text editor is 
useless. I use it, as a word processor, for 
hours every day, with no difficulty; 
however, I'm not hampered by familiar- 
ity with any other text editors. Mr 
Dahmke's statement that the H-89's 
reading of error messages from disk 
takes "several seconds" is, frankly, an 
exaggeration. The actual elapsed time is 
under one second, though it certainly 
seems longer. Also, the disk head does 
not touch down for "each and every sec- 
tor"; it reads the sectors in pairs, 
touching down for every other sector, 
which is noisy and slow enough. 

If you want a sophisticated machine, 
or a fast, high-precision computer, the 
H-89 isn't it. The H-89 is a fine word- 
processing and financial computer, right 
for the user who doesn't want to get 
deeply involved in computer hardware 
and software. 

Jack McKay 

3200 19th St NW 
Washington DC 20010 

Mark Dahmke Replies 

/ thank Mr Pinkston and Mr McKay 
for their comments about my review, 
and for bringing the various "fixes" to 
my attention and to that of BYTE's 
readers. My philosophy for reviewing 
equipment is that 1 am reviewing essen- 
tially what comes out of the box. Any 
updates from readers are greatly ap- 
preciated, but I feel I must give potential 
buyers an accurate indication of what 
the product is like as it comes from the 
manufacturer. As for the other com- 
ments regarding the editor, I will stand 
by my statements in the review. 



Dissecting the 
Speak & Spell Article 

The article published in the September 
1980 BYTE concerning the TI (Texas In- 
struments) Speak & Spell (see "Dissect- 
ing the TI Speak & Spell," by Michael A 
Rigsby, page 76) contains a number of 
serious errors that must have upset staff 
scientists Richard Wiggins and Larry 
Brantingham at TI's Central Research 
Laboratory in Dallas, Texas. 

To suppose that the TMC0281 device 
used in the Speak & Spell is the same as 
the SN76477 is to greatly underestimate 
Texas Instruments' achievement. The 
TMC0281 is, in fact, a complete speech- 
synthesizer device fabricated in metal- 
gate depletion-load p-channel technology 
and contains an entire digital-signal pro- 
cessor, with timing and decoding cir- 
cuits, a ten-stage digital lattice filter, and 
a D/A (digital-to-analog) converter. The 
system is based upon the relatively new 

20 February 1981 © BYTE Publications lnc 



voice-compression technique known as 
linear predictive coding. This technique 
can generate high-quality speech from 
low data rates (less than 2400 bits per 
second). Linear predictive coding is so 
called because of the way in which the 
coefficients that characterize the digital 
filter are predicted from a linear com- 
bination of the previous coefficients. 
This requires a great deal of number 
crunching — in the case of the TMC0281, 
160,000 additions and 160,000 10- by 
14-bit multiplications every second. TI 
confounded the many skeptics who said 
it couldn't be done. To get around the 
speed problem, Wiggins transformed all 
the calculations into a fixed-point format 
and Brantingham designed a pipeline 
processor that is contained within the 
TMC0281. 

The coded speech data for the syn- 
thesizer device is stored in the 
TMC0351's read-only memory. These 
are 16,384 by 8-bit devices (ie: 128 K 
bits) having an internal 18-bit address 
counter/register and two 8-bit output 
buffers. Fourteen of the address bits go 
to the memory array directly, while the 
4 most significant bits are used in a 
l-of-16 chip select. 

The controller chip, the TMC0271, is 
a slightly modified calculator chip, a 
member of the Texas Instruments 
TMS1000 family. It has been modified 
to enhance its BCD (binary-coded 
decimal) arithmetic and expand its in- 
struction set. Also, there is an output 
multiplexer to reduce the pinouts needed 
for the Speak & Spell application. 

Contrary to the implications in the ar- 
ticle that the "operation of the Speak & 
spell involves many unknowns," TI has, 
in fact, published full details of its three- 
chip synthesizer system (see Electronics, 
August 31, 1978, pages 109 thru 116) 
and many other articles have appeared. 
A letter to TI brings (at least in my case) 
a set of reprints. 

Tim Spracklen 

23 Buttermere, Greenways, Spennymoor 

Durham, DL16 6UD, England 



De Facto of De Matter 

This is a plea for order in what could 
be the next standards chaos: Sol Libes 
mentioned a Massachusetts company 
planning to use home VTRs (videotape 
recorders) for hard-disk backup. (See 
"Backing Up Winchesters" in 
"BYTELINES" October 1980 BYTE, 
pages 188 and 189.) Corvus also plans 
such a system. Our company, D C 
Crane lnc, is planning one using the 
Digital Graphic Systems CAT-100 video- 
display board. 

The technique will allow saving and 

Circle 16 on inquiry card. 



A growing 
line of tools to 
expand the Apple. 



7440A Programmable Interrupt Timer Module. 

Time events in four operating modes— continu- 
ous, single shot, frequency comparison, and 
pulse width comparison. Includes three 16-bit 
interval timers, plus flexible patch area for 
external interface. Programmable interrupts, 
on-board ROM, and much more. 

7720A Parallel Interface. Two bi-directional 8-bit 
I/O ports will connect your Apple to a variety of 
parallel devices, including printers, paper tape 
equipment, current relays, external on/off 
devices. Full featured, programmable inter- 
rupts, supports DMA daisy chaining. 

7811 B Arithmetic Processor. Interfaces with 
Applesoft, so you just plug in and run. Based 
on the AM 9511 device, provides full 16/32-bit 
arithmetic, floating point, trigonometric, loga- 
rithmic, exponential functions. Programmed I/O 
data transfer, much, much more. 

7710A Asynchronous Serial Interface. Conform- 
ing to RS-232-C A thru E 1978 standard, this 
card will drive a variety of serial devices such as 
CRT terminals, printers, paper tape devices, or 
communicate with any standard RS-232 device, 
including other computers. Full hand-shaking, 
and fully compatible with Apple PASCAL! 

7470A 3tJ BCD Ay D Converter. Converts a DC 
voltage to a BCD number for computerized 
monitoring and analysis. Typical inputs include 
DC inputs from temperature or pressure 
transducers. Single channel A/D, 400 ms 
per conversion. 

7490A GPIB IEEE 488 Interface. A true imple- 
mentation of the IEEE 488 standard— the 
standard protocol for instrumentation and test 
devices. Control and monitor test instruments 
such as digital voltmeters, plotters, function 
generators, or any other device using the 
IEEE 488. 

7114A PROM Module. Permits the addition to or 
replacement of Apple II firmware without 
removing the Apple II ROMs. Available with 
on-board enable/disable toggle switch. 

7500 A Wire Wrap Board. For prototyping your 
own designs. 

7510A Solder Board. 

7590A Extender Board. 



Watch this space for new CCS products for 
the Apple. We've got some real surprises in the 
works. To find out more about the CCS product 
line, visit your local computer retailer. The CCS 
product line is available at over 250 locations 
nationally, including most that carry the Apple. 
Or circle the reader service number on this ad. 

Apple II, Apple II Plus, and Applesoftaretrademarks 
of the Apple Corporation. 

CCS makes the difference. 



We see the Apple 




We see it as a good 
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Apple has built a great computer. We at CCS have 
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with a computer. 

If you wafit to do business with an Apple, we've got 
tools to connect the Apple to standard business printers and 
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phone lines, with other computers, even with other Apples. 

If you want to apply your Apple to engineering, scien- 
tific, or graphic projects, we've got tools for high-powered, 



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high-speed math functions, and fast, high resolution graph- 
ics. And tools to connect the Apple to lab test equipment 
like function generators or plotters. 

And we have tools to connect the Apple to the outside 
world, including A/D converters and interval timers with 
external interface. 

We make components for the S-100 bus, the PET, and 
the TRS-80, too.We built our products to deliver hard- 
nosed value to the OEM, and to the inventor who knows the 
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To find out how much computer your Apple II can be, 
see things our way. Because for serious users with serious 
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Apple Disk Drive $550 
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Letters ^— ^—^— __ 

restoring hundreds of megabytes. It will 
also establish de facto interchange stan- 
dards. Could we learn from the past7 
Just this once7 Please7 

I would like to hear from anyone in- 
terested in helping develop or use such a 
standard with a view toward document- 
ing the problem and the solutions in an 
article for BYTE. If a formal standards 
commission is interested, so much the 
better. Please write me at the address 
below. I will put you in contact with 
each other and contribute my ideas 
toward a solution. 

David C Crane 
D C Crane Inc 
POB 79286 
Houston TX 77079 



Have You Tried 
onComputlng? 

For fifteen years I have dreamed of 
using a computer for my one-man busi- 
ness. I have tried to find the right one in 
BYTE, on and between the lines. The 
result of my search is the feeling that, to 
become "computerized," I must become 
an expert in mathematics (Boolean and 
otherwise), electronics, hardware, soft- 
ware, semiconductors, integrated cir- 
cuits, languages, and all the rest of the 
stuff. Oh, my aching head! Help, help! 
The computer train is rolling so fast and 
I am unable to climb aboard. 

When I first became "motorized," I 
didn't have to be an expert in mechan- 
ics, thermodynamics, aerodynamics, 
electricity, tire structure, fuel chemistry, 
etc. I simply sat in the car and— without 
any help — taught myself the rules of the 
road. Who can, for a moderate price, 
link together and harmonize some of the 
wonderful programs advertised in BYTE 
to make a system coherent, practical, 
and flexible? 

R E Gilbert 
Jozef Hermanslei 41 
B-2510 Mortsel 
Belgium 

Of course, a computer is much more 
complex than any automobile, but the 
analogy is still valid. People should be 
able to get what they want from a com- 
puter with a minimum of fuss. Until 
then, Mr Gilbert, guides are necessary: 
enjoy the complimentary copy of 
onComputing; she's our sister publica- 
tion for the layman. 



Sharp-Looking TRS-80 

Upon studying the advertisements for 
the new TRS-80 Pocket Computer, I was 
surprised to find the letter Y's original 



22 February 1981 © BYTE Publications Inc 



second function (ie: ¥, for the yen on 
the Sharp PC 1211) deleted. 

If that's the way the Tandy Corpora- 
tion has to lure prospective customers 
into thinking that the Pocket Computer 
is Ail-American made, I pity any 
Japanese importer trying to sell an 
American computer without String-capa- 
bility.... 

Marc H Bruna 
Abrikozenstraat 31 
2564 VK Den Haag 
Netherlands 



Tree Is Root of Problem 

As a fellow member of the University 
of Oklahoma, I feel it necessary to point 
out some of the areas where I disagree 
with Dr Bill Walker's article "Sorting 
With Binary Trees" (October 1980 
BYTE, page 96). These areas will be 
dealt with in the same order as they ap- 
pear in the article. 

First, Dr Walker gives the impression 
that a tree sort is both fast and allows 
deletion of nodes in an efficient manner. 
As he says, a tree sort is faster than a 
bubble sort, but almost any serious sort 
routine will be faster than a bubble sort. 
Likewise, deleting a node from a tree is 
faster than deleting an element from a 
bubble-sorted list, but deleting nodes 
from trees, except in the special cases of 
AVL; B; and 2-3 trees, is not particular- 
ly fast. (See The Design and Analysis of 
Computer Algorithms, by Alfredo Aho 
and Jeffrey D Ullman. Reading MA: 
Addison-Wesley, 1974.) 

Second, students of graph theory tend 
to define a tree as an acyclic graph. (See 
Graph Theory, by Frank Harary. Read- 
ing MA: Addison-Wesley, 1969.) By this 
definition, the object presented in Dr 
Walker's figure 1 is not a tree, but a 
rooted graph. 

Third, Dr Walker states that one way 
of scanning a sorted tree (a binary- 
search tree) would be to first visit the 
leftmost node in each branch, then the 
parent, and finally visit the rightmost 
node, repeating this sequence until 
finished. He proceeds to say that this is 
"tough for computers." However, the 
C-language routine in listing 1, page 24, 
performs Dr Walker's suggested 
algorithm. 

Next, the algorithm used to search a 
tree can be cleaned up considerably, as 
shown in listing 2. The algorithms used 
to delete and add nodes are excellent, 
and rewriting those in C would serve no 
other purpose than to expose the defi- 
ciencies of Pascal. 

We now have nice, short algorithms 
to do everything that Dr Walker wanted 
to do to the tree, except to delete nodes 

Circle 17 on inquiry card. » 



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Circle 18 on Inquiry card. 



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Call or write Artec for details 




Letters. 



from it. As far as I know, the algorithm 
he used cannot be improved upon to 
any great extent. This point is the basis 
for my statement that it is not relatively 
easy to delete nodes from a tree. 

To achieve the operations Dr Walker 
wants (easy insertion and deletion, while 
maintaining a sorted list, plus easy 
searching), I would recommend a 
double-linked list. The algorithms for 
dealing with this structure can be found 
in any good data structures or 
algorithms text. 

Mike Meyer, Student 
University of Oklahoma 
POB 1749 
Norman OK 73070 



J thoroughly enjoyed Dr Walker's arti- 
cle on binary-tree sorting in the October 
BYTE. He presented a subject that often 
receives a boring and confusing treat- 
ment in an interesting and clear manner. 
Since the amount of data I must sort 
daily has recently doubled, the article 
came at the right time. 

Time after time I have seen the subject 
of trees presented in magazines and 
books. Each time I lacked the incentive 
to actually implement a tree structure on 
my system. The whole thing seemed too 
complicated for the results obtained. 
However, Dr Walker provided the push 
I needed to get it going. 

Although some of the coding is redun- 
dant, by the author's own admission, 
and is slightly inefficient in some areas 



(due mostly to the direct conversion 
from FORTRAN and his desire to keep 
the program portable), the program 
makes sense. That sounds simple, but 
many programs don't make any sense at 
all — they just work "somehow." 

Because of the use of highly structured 
subroutines and "standard" BASIC, I 
easily translated the program of his 
listing 1 into Oasis BASIC and modified 
it for operation on strings. This later 
change is simple if the BASIC used 
dimensions a string-array length rather 
than a string length. The modification to 
sort strings requires changing P in lines 
200 and 205, KEY, and ALPHA to string 
variables. It works well and fast. 

I did, however, find one major design 
problem. It is associated with the dele- 
tion of a right terminal node that is not 
the last node in the sorted sequence. 
Both the coding of line 3090 and the 
logic of table 1, Case II, Group B, Sub- 
case 1 call for setting the right link 
pointer of the parent Q to NIL (setting 
RLINK(Q) = NIL). This tells the tree- 
traversal routine that this parent is the 
last item in the tree. Often it is not. 

The proper logic is to set RLINK(Q) 
equal to RLINK(P). In this way, the 
parent Q of the deleted node P will 
point back to the ancestor node, the one 
that follows it in the sorted sequence. If 
the deleted node P was the terminal 
node of the entire tree, its parent, Q, 
will assume this property when the node 
P is deleted. That is the only problem I 
found. 



Listing 1 



dKTGC GLGCTROMiajMC 

605 Old County Rd., San Carlos, CA 94070 
Telephone (415)592-2740 



struct node { 

i n t info ; 

struct node *leftson, *rightson ; 

1 ; 

visit(root) struct node *root; { 

if (root == NULL) return ; 
visit(root -> leftson) ; 
printf("%d ", root -> info) ; 
v isit(root -> rightson) ; 
} 

Next, the algorithm used to search a tree can be 
cleaned up considerably, as shown: 

search ( roo t , item) struct node *root; { 
while (root != NULL) { 

Listing 2 

if (root -> info == item) 

return(root) ; 
if (root -> info > item) 

root = root -> leftson ; 
else 

root = root -> rightson ; 

} 
return (NULL) ; 
1 



24 February 19S1 © BYTE Publications Inc 



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Star and other S-100 systems. 
A/D board. 12-bit precision. 32 single- 
ended inputs. Or 16 differential inputs. 25 
us conversion time. Vectored interrupt. 
$635. Or $725 with 1 to 1000 gain trans- 
ducer amplifier. Works with our thermo- 
couple compensation board and our 4-20 
mA input boards as well. 
D/A board. Four independent channels. 
12-bit precision. Input is binary or 2's com- 
plement. Compatible with all existing I/O 
mapped software. $495. Drives our ampli- 
fier board which outputs 4-20 mA. 
CMOS RAM board. On-board battery 
back-up preserves data a year. 200 ns 
read/write time. Runs at 4 MHz. 8K bytes 
$590. 16K bytes $990. 
CMOS clock board. On-board battery 
back-up keeps clock running a year. New 
LSI chip carries date, hours, minutes and 
seconds. Read or write directly from I/O 
port. Vectored interrupt. $250. 

We also provide complete main- 
frame systems. OEM and dealer inquiries 
are invited. 

Contact Dual Systems Control 
Corp., Dept. B, 1825 Eastshore Hwy., Berke- 
ley, CA 94710. Phone (415) 549-3854. 




Letters , 



Many thanks to Dr Walker. It was a 
great article; I would enjoy seeing more 
articles from him in the future. 

Jack Dolby 

335 D-l Hiddenwood Dr 

Newport News VA 23606 



Screen Print for TRS-80 

In the October BYTE, Teri Li's 
'Technical Forum" talks about some of 
Radio Shack's modifications for the 
TRS-80. (See "Radio Shack's Modifica- 
tions to the TRS-80," page 182.) The 
screen-print problem created by the 
lowercase modification has a simple 
solution. Run the program shown in 
listing 1. 



The screen will display: @ABCD 
EFGHIJKLMNOPQRSTUVWXYZ (up 
arrow) (down arrow) (left arrow) 
(right arrow) (dash) 

This is how TRSDOS prints characters 
to the display. The alphabet codes are 
decimal 1 to 26. If we add 64 to each 
decimal value PEEKed from the display 
that is less than 32, then print the CHR$ 
equivalent to the printer, no problem 
will be encountered. 

The program in listing 2, called as a 
subroutine, will print the contents of the 
display to a line printer. 

This routine works on uppercase and 
upper/lowercase keyboards. 

Gary E Alcorn 
1037 E Redondo Dr 
Tempe AZ 85282 



Listing 1 
10 CLS 

20 FOR A = 15360 TO 15391 
3 POKE A,B 
40 B = B + 1 
5 NEXT A 
60 PRINT 
70 END 
Listing 2 

50 P = 1536() 

5010 FOR V = 1 TO 15 : FOR H = TO 63 
5020 IF PEEK(P) < 32 THEN F'* = CHR* ( PEEK ( P ) + 64) ELSE 

P* = CHR* (PEEK (P ) ) 
5 30 L.PRINT P*J 5 P = P + 1 J NEXT H 
5040 LPRINT" " 
5050 NEXT V 
5060 RETURN 



Pain In the Exhaust 

The article "FCC Regulation of 
Personal- and Home-Computing 
Devices," by Terry Mahn (September 
1980 BYTE, page 180) has consequences 
for buyers and sellers of microcomputer 
systems that are far-reaching and not 
widely realized. 

Compliance with the new FCC 
(Federal Communications Commission) 



regulations and the associated paper- 
work, testing, and certification are ex- 
pensive. Personal- and business-com- 
puter systems will be more expensive 
after the first of January, 1981, because 
the consumer will be paying for com- 
pliance with these regulations. 

Let me first point out that, as a 
licensed radio engineer, I must agree that 
restricting radio emissions from personal 
home-computing devices is both neces- 



26 February 1981 © BYTE Publications Inc 



THE NEW RELIABLES 



We used to be known as Industrial Micro Systems and 
we made the best micro componentry around. 

Now we're IMS International, and the best compo- 
nents in the business are an integral part of the best and 
broadest micro-based business system line around. Ours. 

As a dealer, here is a sales package with real teeth. 

Easy to sell. 

Reliable. Engineered equipment offering factory tech- 
nical support a phone call away. (Though we have 
equipment in operation since 1975, yet to fail.) 

Low cost — well under $10,000 complete — with 
the best margins and benefits in the industry. Face it, 
even the most impressive specifications are no replace- 
ment for profits. 

Our systems are designed to meet the specific needs 



of your business computer customers today and tomor- 
row. Our tested dealer sales package has been designed 
for you and your needs. 

Tailored sales plan. National advertising backup. 
Point of purchase program. Protected territories. 
Guaranteed complete system deliveries in 30 days. 
180-day warranty to your customers. 

We have what you and your customer need. 

The package is complete. New. Reliable. 

To become part of our expanded dealer network in 
1981, call Fred Williams (collect) 714/978-6966, 
or write us: 

Boxl 

2800 Lockheed Way 
international Carson City NV 89701 

Circle 21 on inquiry card. 










p-='/ ; :S 





Well, to begin with, color graphics. 

RCA's VP-3301 has unique color-locking circuitry that gives 
you sharp, jitter-free color graphics and rainbow-free characters. 

Plus much more: Microprocessor control. Resident and 
programmable character set. Reverse video. State-of-the-art 
LSI video control. 20 and 40 character formats. RS232C and 
20 mA current loop. Six baud rates. Eight data formats. ASCII 
encoding. Light-touch flexible-membrane key switches for 
reliability and long life. CMOS circuitry and a spill-proof, dust- 
proof keyboard for hostile environments. 

The VP-3301 can be used with a 525-line color or monochrome 

monitor or a standard TV set through an RF modulator. It 

serves a wide variety of industrial, educational, business and 

individual applications including communication with time 

sharing and data base networks such as those provided by 

Dow Jones News/Retrieval Service, CompuServe and Source. 

All this— for the low price of $369. And it's made by RCA. So 

get the whole story about the surprising VP-3301 today. Write 

RCA Microcomputer Marketing, New Holland Avenue, 

Lancaster, PA 17604. Or call toll-free: 800-233-0094. 



'Suggested user price. Monitor and modem not included. 

©1980. RCA 

28 February 1981 © BYTE Publications Inc 




Letters • 

sary and desirable. The impact of this 
restriction is not yet fully realized by 
businesses or consumers. 

I will discuss both views. My com- 
pany functions as an OEM (original 
equipment manufacturer), buying 
boards, cabinets, floppy disks, etc, from 
various companies and customizing these 
into systems for our customers. We are 
in a favorable location, where the FCC 
is a local telephone call away, and its 
testing labs, in Laurel, Maryland, are 
right up the street. As a business, what 
we have to do to legally advertise or sell 
a system after January 1, 1981, involves 
a lot of work and money. The testing 
and certification are beyond our in- 
house capabilities, and the necessary 
spectrum analyzer — even to rent — is ex- 
pensive. A lab in our area will do the 
testing for us for $1500. Necessarily, this 
forces us to raise our products' prices. 
There, then, is even more involved 
paperwork and such. Now, $1500 is not 
a lot to the Tandy Corporation, Apple 
Computer, or Hewlett-Packard, but it 
does represent a problem for the hun- 
dreds of small computer businesses. 

Also, we believe our main selling 
point is S-100 compatability, whereby 
we can choose from the wide spectrum 
of available boards to customize a user's 
system. However, if we change anything 
that would affect RF (radio frequency) 
emissions (ie: substitute a different in- 
put/output or memory board), we must 
recertify the "new" configuration. This 
will defeat any flexibility we now enjoy. 
The key point is that larger manufac- 
turers can easily absorb these expenses, 
and we "little guys" are forced to raise 
prices drastically, or go out of business. 

For consumers, you'll be paying more 
for a system that is certified to meet RF 
emission/interference criteria. It is hard 
not to draw parallels with emission-con- 
trol equipment required on automobiles. 
In principle, it is an excellent idea. In 
practice, it is a pain in the exhaust, and 
an expense. 

Having presented the problem, let me 
suggest some approaches. Even though 
this matter has been studied by the FCC 
for three years, it is being sprung upon 
manufacturers rather quickly. I believe a 
period of evaluation by the industry — 
particularly the microcomputer "cottage 
industry" — is in order. I have mentioned 
this to the FCC and to my congressman. 
Also, I would be happy to discuss these 
issues with any other interested parties. 

This issue represents a critical turning 
point for our industry and our hobby. I 
do not believe that many people are 
aware of the consequence. 

Patrick H Stakem, President 
Interface Technology of Maryland 
POB 745 
College Park MD 20740a 



Circle 22 on inquiry card. 



THE DAWN OF 
A NEW AGE 




The 2nd Generation is here! 



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Z80 PROCESSOR 
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Hardware Review 




Radio Shack's Daisy Wheel Printer II 



Yvon Kolya, POB 22, Peterborough NH 03458 

In August of 1980, Radio Shack introduced a series of 
new products, including a daisy-wheel printer capable of 
producing high-quality print for word-processing 
systems. Radio Shack named the device the Daisy Wheel 
Printer II. 

I was fortunate enough to be among the first to receive 
one of the new Daisy Wheel Printer lis. I picked it up at 
the store only a week after ordering it. 

Physical Appearance 

As I expected, the printer had an attractive ap- 
pearance, using the standard Radio Shack colors black 
and silver. However, much to my surprise, I found the 
printer to be constructed entirely of heavy-gauge cast 
aluminum. The only nonmetal parts were the miscella- 
neous knobs and switches, which were brought out to the 
surface of the cover for the user to manipulate, and a rub- 
ber platen. Upon opening it up, I discovered that the 
metal exterior was well supported by a cast aluminum in- 
terior frame, with a layer of foam rubber sandwiched be- 
tween the two for sound absorption. Everything else 
seemed to be made of steel or chrome, except the pulley 
wheels, which were nylon. All in all, the printer appeared 
to be very solidly constructed. It was a bargain to get all 
this excellence for hundreds of dollars less than an 
equivalent letter-quality printer. 

Connecting It 

As soon as I had unpacked the printer from its shipping 
box, I plugged the carbon ribbon cartridge into place, a 
very simple operation, and then I pressed the print wheel 



into position (also a very simple operation). When I con- 
nected the printer to my TRS-80 Model II and tried it out, 
it worked perfectly. 

I borrowed a friend's TRS-80 Model I Disk System and 
tried it out with the printer. It also worked perfectly the 
first time. 

Next I connected it to an Apple II-Plus computer, using 
its Parallel Printer Interface Card. Unfortunately, it did 
not work. After a little experimentation, I discovered that 
the problem was with the ROM (read-only memory) soft- 
ware on the parallel card. Normally, the Apple's software 
leaves the eighth bit of the data bus set high. When it's set 
low, the characters on the video display flash on and off. 
On the Centronics printers, and their look-alikes, this bit 
is ignored. On the Radio Shack printer, however, the 
eighth bit is used for the special characters. To correct 
this problem, I grounded the line for the eighth bit, and 
the printer then worked correctly with the Apple II-Plus. 
I could have used a software routine to correct this prob- 
lem, but I felt this method would be quicker. 

Printer Controls 

There are two control switches on the front of the 
printer, an on-line/ off-line switch and the pitch-control 
switch. There are three modes of pitch control: 10 cpi 
(characters per inch), 12 cpi, and proportional spacing. 
The pitch control used depends upon the type font 
mounted in the printer. For example, if the Courier 10 
font daisy wheel is in place, this switch should be placed 
in the 10 cpi position. If the Prestige Elite font is used, the 
switch setting should be 12 cpi. The Madeleine font re- 
quires that the switch be set to proportional spacing. To 
some minor degree, the 10 and 12 fonts can be used at 
either the 10 or the 12 cpi switch setting, although using 



30 February 1981 © BYTE Publications Inc 



Circle 23 on inquiry card. 



?>* 



■%£>! 



<f* 



:^TV 




«£$ 



m-> 



SM 



£P^ 



E 



ZORK is more 
than an adventure. 

Zork'" is a computer fantasy of ultimate challenge. Un- 
earthly creatures guard treasures beyond your imagina- 
f tion. Mazes confound your quest. So quicken your wits 
and pick your path carefully through the Great Under- 
ground Empire. The least likely object 
7 may be the only thing that can save ,..* 

your life. iSSSV 

Yet, you can succeed. Discover the 20 
treasures of Zork, return them to the Trophy 
Case and leave alive. But bring all the cunning 
and courage you can muster. Because in 
Zork, they take no prisoners . . . 

Zork, The Great Underground Em- 
pire, was created by Infocom, Inc., and 
j±.\is available for 32K Apple* II and II 

--Plus and 32K TRS-80'" Model 1 Level I — - 

K 11 disk systems. 
I Also new from Personal Software 

is MONTY '" Plays Monopoly* which 
lets an Apple or TRS-80 play Amer- 
ica's favorite board game with the 
family. 

Arcade Classics is a new TRS-80 
action game featuring Cosmic 
Raiders, Pinball, Ricochet and 
8fc\ Blockade:"' A great way to 
^, J \ have fun without feeding 
quarters into the machines 

Zork, MONTY Plays Mon- 
J3 opoly and Arcade Classics- 
more fun and games with 
your computer, now join- 
ing our other Strategy 
Games: Microchess, 
Gammon Gambler, 
j Checker King, Bridge 
Partner and Time Trek. 
' ./ See these great strat- 

egy games at your Per- 
sonal Software com- 
puter retailer. For the 
I dealer nearest you, call 
| Personal Software Inc. 
at 408/745-7841, or write 
1330 Bordeaux Drive, 
Sunnyvale, CA 94086. 

When you put your 
computer to work, use 
Personal Software'" Pro- 
ductivity Products: VisiCalc,'" 
DESKTOP/ PLAN" and 
CCA Data Management 
System. _ ■ 



"Wg 



ft 



I 4 



v, 



the 10 font at the 12 setting will make the letters appear 
cramped. 

At the top of the printer are two levers, one on the 
right for releasing the grip of the platen on the paper, and 
one on the left for controlling the number of carbon 
copies (from 1 to 7) to be run through the printer. 

At the rear of the printer are, once again, two switches. 
One switch is directly above the power cable, and it is 
used to turn the machine on and off. The other is over the 
interface connector; it is the self-test switch. The self-test 
switch prints out a series of characters to test both the 
printer and the print wheel. 

Inside the printer, to the right of the cabinet, there is a 
three-position impression intensity control switch. It 
allows you to adjust the amount of energy used by the 
strike-hammer when printing. 





Name 


Audience 


Daisy Wheel Printer 


Computer owners desir- 


II — catalog number 


ing letter-quality printout 


26-1158 


instead of dot-matrix 


Use 


Features 


Letter-quality printer 


Print speed: 43 cps; 




carriage-return speed: 


Manufacturer 


300ms/13% inches (34.5 


Radio Shack 


cm); linefeed speed: 4 


1 Tandy Center 


ips; printing pitch choice 


Forth Worth TX 76102 


of y i0 inch, y i2 inch, or 




proportional spacing; 


Dimensions 


linefeed pitch: % inch or 


20.45 by 62.5 by 39.5 cm 


Yi 2 inch; fonts: 124 char- 


W 20 by 24% by 15^ 


acter positions on 


inches) 


double-daisy print wheel; 




wheels: Courier 10 


Price 


(supplied), Prestige Elite 


$1960 


12 (not supplied; catalog 




number 26-1421), 


Hardware Required 


Madeleine P S (not 


TRS-80 Model I, II, or III 


supplied; catalog number 


computer, or any com- 


26-1422); characters per 


puter capable of driving a 


line: 136 characters at 10 


standard Centronics- 


pitch, 163 characters at 


interface parallel printer; 


12 pitch; impression con- 


requires a printer- 


trol: high, medium, low; 


computer cable, available 


interfaces (physical): 


from Radio Shack, for 


eight parallel and one 


whichever Radio Shack 


strobe; code: Modified 


computer the printer is to 


ASCII; paper-feed 


be used with. 


mechanism: pinch-feed 




platen; power 


Software 


requirements: 120 VAC, 


None (if used with 


50/60 Hz, 141 W 220 


appropriate configuration 


VAC, 50 Hz (for 


of a Radio Shack com- 


European operation) 


puter) 




Hardware Options 




Tractor feed, $249 extra 




Documentation 




38-page manual, 22 by 28 




cm (8V2 by 11 inches), 




includes schematics 





Printer Attributes 

This printer does not require special software for use. If 
you have the proper printer cable for your computer, you 
can use the printer immediately. While in BASIC, you 
can use it to print listings, or you can use it from within a 
program to deliver hard-copy information. If you have a 
word processor, such as Radio Shack's Scripsit or 
Michael Shrayer's Electric Pencil, you are really ready to 
go. 

Unfortunately, both Electric Pencil and Scripsit are in- 
capable of using all the features of this printer. For exam- 
ple, not all of the control codes accepted by this printer 
are used by these two word processors. The codes ac- 
cepted by the Daisy Wheel Printer II are given in table 1. 

Unfortunately, Scripsit will access only the carriage- 
return-with-linefeed code (decimal 13) of this printer. The 
rest of the codes are not used. 

Electric Pencil is only a little bit better in that it accesses 
the backspace feature (to perform underlining) in addi- 
tion to the carriage-return-with-linefeed code. 

Fortunately, BASIC is capable of accessing all of these 
codes (using the function CHR$(X)); the printer's manual 
provides several example lines of BASIC code that can be 
used to do this. Listing 1 shows the first step of a maze 
generated on the Apple II-Plus printed by this printer. A 
word of caution: if your BASIC program uses the top-of- 
form code (decimal control code 12), you will need a 
special driver program for this printer. This special pro- 
gram is available from Radio Shack free of charge. 

Although BASIC can access all of the characters and 
control codes used by the printer, the TRS-80 in com- 
mand mode is incapable of accessing either the special 
control codes or about thirty characters on the print 
wheel because the keyboards of the Tandy Corporation 
computers do not generate the necessary ASCII (Amer- 
ican Standard Code for Information Interchange) codes. 

The complete character set produced by the printer is 
shown in listing 2. Notice that there are several foreign- 
language characters, as well as special nonalphabetic 



Listing 1: A test pattern to check registration. This pattern, 
which is made from vertical bars and underline characters, 
demonstrates the printer's capabilities of great printing 
accuracy. 



Listing 2: The character set of Radio Shack's Daisy Wheel 
Printer I!. Some of the special characters can be printed only by 
sending special-character codes to the printer. 

!"#$»& '()*+,-. /0123456789: ; <->?@ABCDEFGHIJKLMNOPQRSTUVWXYZ [\]"_" 
' abcdef ghi jklmnopqrstuvwxyz { | } ~ag£u ° 't" 9 ® H i5sue"f §¥A0Ut_a6uG 



32 February 1981 © BYTE Publications Inc 



Circle 24 on inquiry card. 




"•I* 



How to tell if it's a White Computer. 



You see, it isn't always white. 
Until now, if you bought a White 
Computer it was dressed up as some- 
one else's system. Mow the White 
Computer is available under its own 
nameplate. 

And the features that make the 
White Computer the choice of many 
system builders also make the White 
Computer an excellent choice for you. 

Features like White's guaranteeto 
ship replacement parts within 24 
hours of your telephone call. CP/M® 
and MP/M™ operating systems. Full 
upgrade routes to multi-user and 
hard-disk performance. (Like the 
3-user 35 megabyte system shown.) 
And 8-bit or 16-bit configurations. 
Features that make the White Com- 
puter the reliable, high performance 



system you need for business, or 
software development, or industrial 
control uses. 

So if you buy a computer that's 
not white, it might still be White. But 
make sure. Because if it's not White, 
chances are you're paying more, for 
less computer. 

White Computers are now 
available from computer dealers 
nationally. Call or write for more 
information, and the name of your 
nearest dealer. 

CP/M is a registered trademark of Digital Research. 
MP/M is a trademark of Digital Research. 




White Computer Company A 1876 Industrial Way 
Redwood City, California 94063 A 415 364 7570 




Photo 2: The print-wheel mechanism. The print wheel is a 
double-daisy wheel (ie:. each prong of the wheel contains two or 
more characters, one closer to the center than the other). The 
mechanism is shown tilted back, which is the position used for 
changing the print wheel. 



Code (decimal) Description 


10 


Linefeed, no carriage return 


13 


Carriage return with linefeed 


27,10 


Reverse linefeed 


08 


Backspace one character 


15 


Turn on automatic underline, all subsequent 




characters will be underlined 


14 


Turn off underline 


27,01 


Space V 60 of an inch 


27,02 


Space V 30 of an inch 


27,03 


Space V 20 of an inch 


27,04 


Space V 15 of an inch 


27,05 


Space V, 2 of an inch 


27,06 


Space 7 10 of an inch 


27,14 


Software set printer to '/,„ of an inch character- 




space mode 


27,15 


Software set printer to V, 2 of an inch character- 




space mode 


27,17 


Software set printer to proportional spacing 


27,28 


Half linefeed 


27,30 


Reverse half linefeed 


Table 1 Control codes accepted by the Radio Shack Daisy 


Wheel Printer I!. Some of the operations are performed with 


a two-code 


sequence. 



characters. Careful study of the type font indicates that 
the Courier 10 print wheel supplied with the printer is 
capable of printing both the French and German alpha- 
bets. That's a really nice feature, if your software will 
allow you to generate the required ASCII codes from the 
keyboard. 

Another worthwhile feature of this printer is a printer 
optimizer. If a series of linefeeds, either positive or 
negative, are received by the printer within 10 ms of each 



DEALERS... OEM USERS. 

Call on Monday... 
your North Star 
computer 
will be 

dldltkmmil by 
Thursday. 




WHOLESALE PRICES 
AVAILABLE. 

Authorized stocking 
distributor for North 
Star. GBC also main- 
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the following prod- 
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• Centronics 

• Perkin-Elmer 

• Epson 



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other, they are temporarily stored until a character code 
or control code is received, after which they are all per- 
formed at once. That is, if ten linefeed codes are received 
at less than 10 ms intervals, they are automatically 
stored. Upon receipt of the eleventh code, which in this 
example is not a linefeed, the printer moves the paper the 
full distance of ten linefeeds, rather than the distance of 
one line ten times, as other printers do. 

As a last note, the documentation says that the printer 
uses a multistrike carbon ribbon. This means that the rib- 
bon is advanced very slowly, with each key striking on 
almost the same place as the previous keystroke. Unfor- 
tunately, when the end of the cartridge is reached, you 
cannot rewind it and reuse the ribbon unless you disas- 
semble the cartridge and rewind the ribbon from the take- 
up reel to the supply reel by hand. This is a very tedious 
and messy process. (I did it once when I desperately need- 
ed a printout and did not have an extra cartridge avail- 
able.) 

Summary 

• Radio Shack's Daisy Wheel Printer II is a full-featured 
printer capable of providing high-quality print; it is total- 
ly suitable for use in word processors. 

• The printer accepts the Centronics-standard parallel 
connector; thus it can be driven by any computer capable 
of driving a Centronics-type parallel printer (although 
some modification may be necessary to prevent the print- 
ing of special characters that use the eighth bit high). 

• The print wheel supplied provides 124 different 
characters, not all of which can be produced from the 
standard ASCII keyboard unless a special software- 
driver routine is written and used. 

• The printer is constructed of heavy-gauge metal and 
should be capable of heavy-duty use for a very long and 
useful life. 

• According to a label on the back, the printer was made 
in Japan for Radio Shack. If someone had told me that 
Radio Shack would be selling a word-processor printer as 
solidly built as an NEC (Nippon Electric Company) 
printer or a Diablo Spinwriter, only much cheaper, I 
wouldn't have believed it. Now I do.B 



34 February 1981 © BYTE Publications Inc 



Circle 25 on Inquiry card. 



* * * A PERCOM BULLETIN * * * 

Adapter for TRS-80* computer eliminates disk read errors 



Garland, Texas — Harold 
Mauch, president of Percom 
Data Company, announced 
that the company is marketing 
a simple plug-in adapter for 
TRS-80* computers that cor- 
rects a design deficiency in 
the disk controller circuit. 

The problem, which 
causes disk read errors, has 
been traced to Tandy's re- 
liance on a circuit internal to 
the FD1771 controller IC to 
perform the function of 
separating clock and data 
pulses. 

As explained in the 
Backgrounder, use of the in- 
ternal chip circuit for reliable 
data-clock separation is a de- 
sign shortcut which the man- 
ufacturer of the controller IC 
warns against. 

The Percom solution, a 
PC card adapter called the 
SEPARATOR™, eliminates 
the problem by substituting an 
explicit data separator circuit 




SEP.. 1771 

CLOCK PiN ?b 



SEP. 17 71 
DATA PIN 2 7 



1771 

S p 1 N 2 5 



RATOR 



DATA CO. INC. 



Percom adapter fixes TRS-80* \computer disk controller. 

— one which has been used The SEPARATOR™ is 

reliably in Percom disk con- installed without modifying the 

trailers since 1 977 — for the host system. The user merely 

internal IC separator circuit. removes the FD1771 IC from 



the host controller, installs the 
IC in the DIP socket on the 
SEPARATOR™ card, and 
plugs the adapter into the va- 
cated socket of the host con- 
troller. 

Percom cautions that 
opening the Expansion Inter- 
face of the TRS-80* comput- 
er, which is required to install 
the SEPARATOR™, may void 
the computer's limited 90-day 
warranty. 

The SEPARATOR™, 
which sells for $29.95, may 
be purchased from Percom 
dealers or ordered direct from 
the factory. The Percom toll- 
free order number is 1- 
800-527-1592. 

Payment for mail orders 
may be made by certified 
check, cashier's check or 
money order, or charged to a 
Master Card or VISA account. 
Texas residents must add 5% 

SaleS taX. Circle 26 on Inquiry card. 



Percom Mini-Disk Drives 
Store More, Cost Less. 

Percom mini-disk drives store more data, are 
more reliable, yet a 40-track Percom drive 
costs $100.00 less than a 35-track Tandy 
drive. 

You can store over 1 02 Kbytes per disk 

on Percom TFD-100™ 40-track drives, over 

197 Kbytes per disk on TFD-200™ 77-track 

drives. A patch — supplied free on minidiskette — upgrades 

TRSDOS* for operation with the newer 40- and 77-track drives. 

Both TFD-100™ and TFD-200™ models are available in 

one-, two- and three-drive configurations. 

Prices start at $399 for a single-drive TFD-1 00™, $675 f ora 
single-drive TFD-200™. Drives are supplied with heavy-duty 
power supplies. Metal enclosure is finished in compatible silver 
enamel. 

See your nearby Percom dealer or order direct by calling 
toll-free 1 -800-527- 1 592. circi„ *a on inquiry c »rd. 




Five-Inch Disks Store More 
Than Eight-Inch Disks! 



Garland, Texas — June 25, 
1980 — Percom Data Company 
has begun production of a 
double-density disk controller 
adapter for TRS-80* Model I com- 
puters. 

Harold Mauch, president of 
Percom, made that announcement 
here today, saying that data stor- 
age capacity using the adapter and 
double-density disk operating sys- 
tem — which is included — can be 
increased to as much as 354 
Kbytes per minidiskette. 

By comparison, the maximum 
storage for larger eight-inch disk 
systems used with the TRS-80* 

Circle 322 on Inquiry card. 



Model I computer is about 290 
Kbytes. 

Mauch said the PC card adap- 
ter, which plugs into the controller 
chip socket of the computer Ex- 
pansion Interface, works equally 
well for either single-density or 
double-density storage, and users 
may continue to run programs 
under TRSDOS*, OS-80™ and 
other single-density operating sys- 
tems with the adapter installed. 

Price, for the plug-in adapter, 
the TRSDOS*-like double-density 
DOS and a utility for converting 
files and programs from single- to 
double-density format is $219.95. 



BACKGROUNDER 

CRC ERROR! TRACK LOCKED OUT! 

by the Technical Staff 
Percom Data Company 



This problem started while 
we were studying an annoying 
problem with the TRS-80* com- 
puter. Disk drives sold by Percom 
are realigned and tested before 
shipment. We noticed, however, 
that some disk drives would pass 
the Percom inspection but just 
would not work reliably on the 
inner tracks with a TRS-80* com- 
puter. These drives were within 
the manufacturer's specifications, 
and would function perfectly on 
other disk systems Percom man- 
ufactures — "perfectly" here 
meaning more than 50 million 
bytes read without error! 

The disk read data separa- 
tion arrangement in the TRS-80* 
computer Expansion Interface 
uses an internal data separator of 
the FD1771 disk formatter/con- 
troller IC. Use of the FD1771 in- 
ternal data separator is not 
recommended by Western Digital, 
the IC manufacturer. The follow- 
ing note appears on page 17 of 
the FD1771 datasheet: 

Internal data separation 
may work for some appli- 
cations. However, for ap- 
plications requiring high 
data recovery reliability, 
WDC recommends exter- 
nal data separation be 
used. 



PRICES AND SPECIFICATIONS SUBJECTTO CHANGE WITHOUT NOTICE. 



We suspected the data 
separator because the problem 
was most severe on disk inner 
tracks where storage density is 
highest and data separation is 
most critical. 

To prove our point, a techni- 
cian breadboarded a standard 
Percom data separator circuit, 
and configured it to plug directly 
into the FD1771 IC socket of the 
TRS-80* computer controller. 

When connected to the 
TRS-80* computer, a trouble- 
some drive functioned perfectly! 
We ran a BACKUP utility many 
times and never got a track lock- 
out. Before we added the external 
data separator circuit to the com- 
puter, this same drive would al- 
ways lock out tracks, and would 
have difficulty reading from the 
inner (higher number) tracks. 

The Percom data separator 
circuit fixes the mini-disk control- 
ler of the TRS-80* computer. The 
type of drives being used is ir- 
relevant; the circuit eliminates 
disk read errors resulting from the 
inability of the Tandy controller 
design to reliably separate clock 
and data signals when reading 
high density inner tracks. 

Circle 323 on Inquiry card. 



PERCOM DATA COMPAMY, IMC. 211 N. Kirby Street Qarland, Texas 75042 (214) 272-3421 

"traiemark o I Percom Data Company, Inc. 'trademark of Tandy Radio Shack Corporation which has no relationship to Percom Data Company. 



An Extremely 

Low-Cost Computer 

Voice Response System 



A computer speech-output system 
can be built which requires no A/D 
(analog-to-digital) or D/A (digital-to- 
analog) converters, no multiple-pole 
filters, no complex hardware, very 
little software, and yet produces 
speech which is quite intelligible even 
to untrained listeners. 

A data rate of 9600 bps (bits per 
second) produces speech quality and 
intelligibility acceptable for most 
hobbyist applications. This means 
that a 400-word vocabulary can be 
stored on one side of a single-density 
8-inch floppy disk, the average word 
duration being 0.5 seconds. Similar- 
ly, the 16 hexadecimal digits, thru 
F, can be spoken from the data stored 
in only 8 K bytes of memory, the 
average word duration for these 
digits being 0.4 seconds. The memory 
need not be high quality, and slow 
memory devices or components with 
a few random bit failures can be used. 
Thus, for limited vocabularies, the 
MIMIC speech processor may be the 
lowest-cost computer speech- 
processing system available. Other 
applications include: 

• two-tone telephone-signal decoding 

• alarm signal 

• automatic word recognition by 
computer (using software pattern 
matching against stored speech 
samples) 

• sound effects 

• computer-generated musical tunes 

• metronome 

• rhythm generator 



James C Anderson 

c/o MIMIC Electronics 

POB 921 

Acton MA 01720 



About the Author 

James C Anderson is a graduate student at 
the Massachusetts Institute of Technology. He 
is the inventor of the MIMIC speech processor, 
a device similar to the one described in this arti- 
cle, which is manufactured and marketed by 
MIMIC Electronics Company. 



A good deal of redundancy is 
maintained at 9600 bps since, for ex- 
ample, a lower data rate is achievable 
by the linear predictive coding 
method (typically 2400 bps). This im- 
plies that slightly defective memory 
circuits can be used for storing the 
speech, with essentially no degrada- 
tion in speech quality (do not base the 
cost of a speech-storage system on 
high-priced memory). The low cost, 
high reliability, ease of use, and mass- 
producibility of this system make it a 
good choice for consumer products 
such as video games. Imagine what a 
computer could say when it finds 
itself losing a game (onomatopoetic 
responses such as "awww" are also 
possible). 



Sixteen spoken 

words can easily 

be stored In 8 K 

bytes of memory. 

There are basically two reasons 
why speech-storage memory can be 
inexpensive: 

• The manufacturer's yield on perfect 
circuits plus slightly defective circuits 
(those with 1 % of the bits bad) will be 
higher than the yield on perfect cir- 
cuits alone. 

• Memories with slow access times 
can be used. An access time of 10 ms 
is more than adequate, and circuits of 
this sort can be purchased at prices 
far below those of standard semicon- 
ductor memories. 

Hardware 

The technique to be used here is 
called differentiated, infinitely 



clipped, and integrated speech. Figure 
1 on page 38 is a diagram of the essen- 
tial hardware. Model speech is input 
through a microphone and a 
preamplifier (ICl). The unprocessed 
analog-speech signal is then used as 
input to a compressor consisting of an 
operational amplifier (or op amp, 
IC2), two diodes, and two resistors. 

The compressor has a pseudo- 
logarithmic characteristic and greatly 
amplifies low-level signals while 
somewhat attenuating high-level 
signals. In this system, the com- 
pressor acts as a simple automatic 
gain control, making the amplitude of 
the speech signal at the compressor 
output less dependent upon such 
things as the human speaker's voice 
loudness and distance from the 
microphone. 

The output of the compressor goes 
to a simple R/C (resistor/capacitor) 
differentiator which has a pole at ap- 
proximately 8 kHz. The differentiator 
performs quite well over the entire 
range of speech frequencies from 
100 Hz to 5 kHz (300 Hz to 3 kHz is 
considered "telephone quality" band- 
width for speech signals). 

The differentiated analog-speech 
signal is then applied to a comparator 
(IC3) which acts as a zero-crossing 
detector, or infinite clipper, and turns 
the analog speech into a digital bit 
stream. A resistor is in series with the 
noninverting input to compensate for 
the input bias current of the com- 
parator, thus preventing distortion 
due to "center clipping" of the signal. 
Only a small amount of DC offset 
potential in the comparator produces 
a large degradation in speech in- 
telligibility. 

This would complete the speech 
data-input path except for one prob- 
lem: when no speech is present, the 



36 February 1981 © BYTE Publications Inc 



Speech Processing 

Many techniques now exist for 
speech processing or digitization 
(the encoding, storage or transmis- 
sion, and subsequent decoding of 
data for speech signals). Some 
techniques have definite advan- 
tages over others depending upon 
the application. 

For example, phoneme syn- 
thesizers, which are essentially 
electrical analog models of the 
human vocal tract, can produce 
speech from very low data rates 
(600 bps (bits per second) or less) 
and are often used in systems 
where bandwidth or memory is 
at a premium. By contrast, time- 
domain techniques such as delta 
modulation require greater band- 
width (9600 bps or more) and are 
popular when a mass-storage 
device (eg: a disk drive) is 
available. Time-domain tech- 
niques simply record speech-signal 
parameters as a function of time, 
and may or may not make use of 
human-vocal-tract characteristics 
to help reduce memory or band- 
width requirements. 

Cost constraints often determine 
which type of speech processor 
will be used in a system. Syn- 
thesizers can be costly both in 
terms of the initial hardware in- 
vestment and in the programming 
and testing time required to con- 
vert words into phoneme strings. 
Neither of these costs is likely to be 
reduced significantly. It is often 
more cost-effective to invest in 
equipment of general utility, such 
as a floppy-disk drive, and use a 
low-cost time-domain speech pro- 
cessor. Many forces are acting to 
drive down the cost of mass 
storage. For example, optical 
recording technology has pro- 
duced a 30 cm disk with storage 
capacity of 10 billion bits and data- 
access times compatible with 
speech-processing requirements. 
Assuming the speech data has been 
sampled at a rate of 16,000 bps, 
such a disk can store enough data 
to produce speech continuously for 
more than a week. 

Many of the time-domain tech- 
niques for speech processing have 
significant drawbacks. Pulse code 



modulation, as used in telephone- 
quality systems, requires a high 
data rate (64,000 bps) and is 
therefore seldom considered for 
present-day computer speech ap- 
plications. CVSD (continuously 
variable slope delta) modulation 
produces good-quality speech 
from a 16,000 bps data stream, and 
several manufacturers have recent- 
ly introduced CVSD integrated cir- 
cuits (MC3417 by Motorola, 
HC-55516 by Harris Semiconduc- 
tor, and FX-209 by Consumer 
Microcircuits of America are ex- 
amples). However, all the CVSD 
units are sole-sourced (ie: non- 
interchangeable with other units). 

Each of these components re- 
quires a considerable amount of 
support circuitry for operation, in- 
cluding a power supply, 
microphone preamp, audio power 
amp, and complicated filter s which 
use precision (1%) capacitors and 
resistors. Perhaps the greatest 
drawback to CVSD is the fact that 
the speech data stream which a 
CVSD chip produces is meaningful 
only to another CVSD chip. 

For example, if the highly encod- 
ed CVSD speech data is to be used 
for automatic word recognition, it 
must first be decoded by some 
rather time-consuming software 
before any operations such as fre- 
quency analysis can be performed. 
CVSD data also proves to be dif- 
ficult to "conference" (mix) in com- 
munication networks, when 
several users are talking 
simultaneously to a single listener. 

When time-domain techniques 
are used to store a large 
vocabulary in memory, it often 
becomes a difficult and time- 
consuming task to reproduce the 
words in the vocabulary at the 
same volume level. This occurs 
because it is nearly impossible to 
hold the microphone in the same 
manner and to speak always at the 
same volume level when originally 
recording the vocabulary. It is also 
difficult to add new words to an 
existing vocabulary for the same 
reason. A similar problem arises 
when attempting automatic speech 
recognition with a computer, since 
variations in volume produce 



variations in the speech data pat- 
tern. Such variations must usually 
be eliminated by a lengthy 
amplitude-normalization process 
in software. 

The MIMIC Speech Processor 
presented in this article is a low- 
cost time-domain system which 
has a relatively low bit rate. Using 
only standard components, the 
MIMIC Speech Processor requires 
minimal external hardware for 
operation. The data produced is 
not highly encoded, and is 
therefore easy to analyze and use 
in communication networks. The 
MIMIC Speech Processor auto- 
matically normalizes the amplitude 
of all audio input signals, and is 
therefore not subject to the prob- 
lem of volume variation. 

Speech Intelligibility 

A common method for evaluat- 
ing speech intelligibility is the "ar- 
ticulation test. " Typically, a per- 
son reads a list of syllables or 
unrelated words to an "untrained" 
group of listeners (recognition 
ability improves with practice), 
and the percentage of items iden- 
tified correctly is taken as the ar- 
ticulation score. By choosing test 
material representative of the 
sound statistics of a language, a 
realistic test of the system can be 
made. Word-articulation scores 
for speech which has been differen- 
tiated, infinitely clipped, sampled 
at a 10 kHz rate, and integrated (in 
that order) are in the neigh- 
borhood of 90% for trained 
listeners. 

When words are used in 
sentences, contextual information 
is present which leads to con- 
siderably higher articulation 
scores. To test your system, try 
recording the sentences "Joe took 
father's shoe bench out, " and "She 
was waiting at my lawn." 
Together, these sentences contain 
all of the fundamental sounds in 
the English language that con- 
tribute toward the loudness of 
speech. 



February 1981 © BYTE Publications Inc 37 



Figure 1: Speech-processing hardware. 
Model speech information is input 
through a microphone and preamplifier. 
The analog signal is processed by com- 
pressor and differentiator circuits, and is 
then applied to a zero-crossing com- 
parator. The result is a serial data stream 
in which the bit width is modulated to 
reflect the input frequency. A squelch cir- 
cuit is provided to disable the processor 
output when no speech signal is present. 




Ai 



fi 1 



comparator (IC3) puts out unpleasant 
high-frequency noise. This problem is 
overcome by controlling the pro- 
cessed speech-data signal with a 
squelch signal. 

The squelch circuit uses amplitude 
information to shut off the data 
stream through IC4a. When the 
overall magnitude of the unprocessed 
input signal is above a certain 
threshold value, the circuit quickly 
enables the data to pass. Op amp IC5, 
diode Dl, and the R/C output filter 
form an envelope-detector system 
which follows the positive peaks of 
the unprocessed speech signal. A 
comparator with hysteresis (IC6 and 
its voltage-divider feedback network) 
is used to give the squelch circuit a 
fast attack response, but a slow decay 
characteristic. Thus, the differen- 
tiated and infinitely clipped digital 
speech data stream is created, and 
squelched when necessary. 

The processed speech, in the form 
of a bit stream, may then be sampled 
by a computer or other digital hard- 
ware at a rate of approximately 
10 kHz. The information may be 
stored in some type of memory, and 
used later to produce speech. 

To reproduce stored speech, the in- 
formation is dumped at a 10 kbps 
rate. The speech-output hardware is a 
filter consisting of IC4c and an R/C 
network which has a pole at approx- 
imately 16 Hz. The buffer (IC7) feeds 
an AC-coupled power amplifier (IC8) 
with volume control. The speech pro- 
duced by this digital recording system 
has essentially been differentiated 
before storage, then integrated upon 
playback. 

Quality 

Although the storage requirement 
is typically 10,000 bits for each sec- 
ond of speech, the effective amount 
of storage required can be reduced 
somewhat by using phoneme con- 
catenation. For example, the spoken 
word "seven" can be stored as an "s" 
sound plus an "eh-vun" sound. The 
same "s" sound can also be used in 
other words such as "six " ("s" plus 
"ick" plus "s"). Similarly, one record- 
ing of the word "teen" will allow you 
to generate "seventeen" with a simple 
program which outputs "s" plus "eh- 
vun" plus "teen." 

This method, unfortunately, will 
not always produce acceptable 
speech. When "dog" is broken up into 
"duh" plus "aw" plus "guh," the 



38 February 1981 © BYTE Publications Inc 



resulting audio does not sound like 
the intended word. This is due to the 
fact that in natural-sounding speech, 
the end of one phoneme often blends 
into the start of the next (but not 
always, as was shown in 
"seventeen"). If all of the phonemes 
are recorded separately, some 
method is needed to blend them 
together — a formidable task. 

The speech quality of this system is 
similar to a single-side-band radio 
signal which is not quite tuned in. 
The speech produced is quite intelligi- 
ble yet rather "mechanical" sounding. 
However, upon listening to speech 
produced by this system, several peo- 
ple have remarked that it "sounds just 
like you'd expect a computer to sound 
when it talks." Thus, it seems to have 
good public acceptance as far as 
quality is concerned. 

Theory 

Why does such a simple system 
work? The answer is not particularly 
simple. However, an understanding 
of the theory can point to methods 
for improving the speech quality and 
can also give a feel for the system's 
limitations. During World War II, it 
was discovered that a large amount of 
peak clipping could be impressed on a 
speech signal with the speech re- 
maining at least moderately intelligi- 
ble. 

Infinite clipping is a process which 
preserves only the zero-amplitude 
axis-crossing information of the 
speech waveform (ie: the process tells 
us whether the signal is positive or 
negative). The intelligibility of an in- 
finitely clipped speech signal can be 



dramatically improved if the clipper 
is preceded by a differentiator circuit. 
A simplified conceptual diagram of 
the hardware is presented in figure 2, 
which omits the squelch circuit. The 
system input /(f) in figure 2 cor- 
responds to the compressor output 
(IC2) of figure 1. 



The spoken word 
"seven" can be 
stored as an "s" 

sound plus an 
"eh-vun" sound. 



Mathematically, taking the 
derivative of a function and equating 
it to zero yields the local maxima and 
minima (peaks and valleys) of the 
original function. For example, 
assume that the system input in figure 
2 is a sine wave, /i(f), as shown in 
figure 3a on page 40. This sine wave 
is differentiated so that the cosine 
wave, /1(f), of figure 3b is present at 
the input to the comparator. Notice 
that whenever /[(f) equals zero, as at 
f = 7r/2, the original function f t (t) is at 
a peak or a valley. 

In the next step of processing, the 
comparator acts as an infinite clipper. 
The comparator output is high when 
/'(f) is greater than zero, which means 
that the original function /(f) has a 
positive slope and is rising from a 
valley to a peak. Similarly, for /'(f) 
less than zero, the comparator output 
is low, which means /(f) is going from 
a peak to a valley. When /'(f) equals 



zero, a critical point is occurring and 
the comparator output is changing. 
The comparator output is an infinite- 
ly clipped version of /'(f) as shown in 
figure 3c. This may be sampled and 
stored as digital information. 

An approximation to the original 
function /(f) can be obtained by in- 
tegrating the stored digital informa- 
tion (see figure 3d). Note that only a 
triangular-type waveform can be ob- 
tained at the integrator output 
because the input to the integrator is 
always a bivariate (two-level) 
waveform. However, a triangle wave 
is a close approximation to a sine 
wave. In fact, the triangle wave of 
figure 3d is given in Fourier-series 
form as: 



(4/7r) [sin f 
(l/25)sin 5f 
+ ...)] 



(l/9)sin 3f + 
(l/49)sin It 



The components other than the fun- 
damental (sin f) can be considered as 
contributions to distortion and can be 
reduced by filtering. In general, a DC 
offset may also be present, but any 
offset can easily be eliminated in the 
actual implementation simply by us- 
ing AC-coupled amplifiers. In sum- 
mary, the system of figure 2 will pro- 
vide a triangle wave which can only 
approximate the original sine wave. 

Amplitude Decoding 

In the system of figure 2, the fre- 
quency of the "reconstructed" wave- 
form (at the output) will be the same 
as the original input frequency. 
However, the output waveform's 



-31- 



>f(u 




SAMPLE BIT STREAM 
AT 10 kHz RATE 



111 



STORE DATA 
IN MEMORY 



OUTPUT BIT STREAM 
AT 10 kHz RATE 



COMPARATOR 



COMPUTER 



T 

X 



^> + 



f'tt) 
if cm 



-O- 



DIFFERENTIATOR 



INTEGRA TOR 



Figure 2: Diagram of the processing concept. This simplified diagram omits the squelch and compressor stages of figure 1. The process 
is easy to follow: any analog input is differentiated and clipped before storage as a digital bit stream; upon playback, the bit stream is 
simply integrated to recover the original waveform information. 



February 1961 © BYTE Publications Inc 39 








1 



n 



\y\y\/\X\ 



40 February 1981 © BYTE Publications Inc 





Figure 3: The basic process is illustrated 
on the first four waveforms. If a sine wave 
(a) is fed to the processor (fM =sin t), the 
wave will be differentiated to produce a 
cosine wave (b) (f[(t)=cos t). Notice that 
the cosine wave crosses zero whenever the 
sine reaches a peak. This is also reflected 
in the output of the infinite clipper stage 
(c) where the waveform may be expressed 
as: f'M/\f[(t)\. At this point, the infor- 
mation may be stored digitally. An ap- 
proximation of the original signal (f(t)) 
can be obtained by integrating the stored 
information to produce (d): 



f'M 



dt 



Although the output waveform has the 
same frequency , the amplitude is not 
always accurately reproduced, since the 
comparator has a constant amplitude out- 
put regardless of input signal level. If the 
signal shown in (e) is fed to the speech 
processor (f 2 (t) = sin 6.5t), the differen- 
tiator will produce the wave of (f) 
(f' 2 (t) = 6.5cos 6.5t). The zero-crossing 
comparator produces the square wave of 
(g) (fi(t)/\fi(t)\), which may be recorded 
quite accurately. When this information is 
played back, the wave of (h) will be pro- 
duced: 



f'M 



dt 



The amplitude is reduced because the 
integrator stage is essentially a low-pass 
filter. The same process is performed on 
more complex waveforms as shown: 

(i) h(t) = sin t + — sin(6.5t + 2.3) 
6.5 

(J) f'i(t) = cos t + cos(6.5t + 2.3) 

fM 



(k) fL,ppJt) 



\W\ 



(!) \Hc t ,„Jt)dt = i~ 
J \fl 



m) 



\M)\ 



dt 



Note that the overall wave shape and 
relative amplitudes are well preserved. 




1 2 3 



amplitude will diminish as the fre- 
quency increases; and it will do so 
regardless of the input amplitude. For 
example, assume that the input to the 
system is / 2 (f) = sin 6.5t, as shown in 
figure 3e. The output of the differen- 
tiator is then /2(f) = 6.5 cos 6.5t, 
which is a large-amplitude cosinusoid 
(see figure 3f). This signal is applied 
to the comparator and the square 
wave of figure 3g results, with an 



February 1981 © BYTE Publications Inc 



41 



amplitude independent of the input- 
signal amplitude. 

The square-wave signal is now run 
through an integrator, which 
drastically diminishes the amplitude 
of the signal (see figure 3h). This is so 
because an integrator acts as a low- 
pass filter, and causes a signal's 
amplitude to diminish in inverse pro- 
portion to its frequency (ie: it at- 
tenuates higher frequencies by 20 dB 
per decade of increase in frequency). 
Thus, the amplitude of f 2 (t) was not 
preserved in the reconstruction, even 
though the frequency was. 



The clipped-speech 

approach presents 

an alternative to 

more complex 

and costly systems. 



We can get an accurate reconstruc- 
tion of both frequency and relative 
amplitude only if we guarantee that 
the input waveform will diminish in 
amplitude as a function of its frequen- 



Listing 1: The author's MIMIC driver. Assembled on Cromemco's CDOS for Z80s, this 
routine should work equally well on any 8080-based microcomputer. As noted in the 
comments at the top, this software should produce a 10 kbps data rate for systems with 
a 2 MHz clock. 







0001 


EXAMPLE: 


MIMIC DRIVER PROGRAM 






0002 


8080 OR Z80 INSTRUCTIONS 






0003 


ASSUMES 4 K OF MEMORY AT LOCATIONS TO FFF 






0004 


ASSUMES MIMIC INTERFACED AT PORT B3 HEX 






0005 


ASSUMES 2 MHZ CPU CLOCK 






0006 


RESULTING SPEECH DATA RATE IS 10 KHZ 






0007 










0000 




0008 




ORG 





PROGRAM STARTS AT ZERO 


0000 


214800 


0009 


/IN 


LD 


HL.BUF 


ADDRESS BUFFER MEMORY 


0003 


0E08 


0010 




LD 


C,8 


INITIALIZE BITCOUNT 


0005 


DBB3 


0011 


vM 


IN 


A.0B3H 


DIG OUT ACTIVE? 


0007 


17 


0012 




RLA 




CHECK FOR BIT 7 SET 


0008 


DA0500 


0013 




JP 


C.V1 


WAIT FOR IT 


000B 


DBB3 


0014 ' 


72 


IN 


A.0B3H 


GET DATA BIT FROM MIMIC 


000D 


IF 


0015 




RRA 




SHIFT BIT ZERO INTO CARRY 


000E 


7E 


0016 




LD 


A,(HL) 


GET DATA BYTE 


000F 


IF 


0017 




RRA 




PUT BIT INTO BYTE 


0010 


77 


0018 




LD 


(HL),A 


STORE DATA IN BUFFER 


0011 


0D 


0019 




DEC 


C 


COUNT BIT 


0012 


C21E00 


0020 




IP 


NZ.V3 


DONE WITH BYTE? 


0015 


0E08 


0021 




LD 


C,8 


RESET BITCOUNT 


0017 


23 


0022 




INC 


HL 


MOVE POINTER 


0018 


7C 


0023 




LD 


A,H 


SET UP FOR COMPARE 


0019 


FE10 


0024 




CP 


010H 


AT 4 K BOUNDARY? 


001B 


CA2400 0025 




JP 


Z.VOT 


YES, NOW PLAY BACK DATA 


001E 


CD4100 


0026 ' 


73 


CALL DEL 


100 MICROSECOND WAIT 


0021 


C30B00 


0027 
0028 




JP 


V2 


LOOP AGAIN 


0024 


214800 


0029 


</OT 


LD 


HL.BUF 


ADDRESS BUFFER MEMORY 


0027 


0E08 


0030 




LD 


C,8 


SET BITCOUNT 


0029 


7E 


0031 ' 


/T2 


LD 


A,(HL) 


GET DATA BITS 


002A 


D3B3 


0032 




OUT 


0B3H.A 


OUTPUT DATA TO MIMIC 


002C 


OF 


0033 




RRCA 


ROTATE BITS IN DATA BYTE 


002D 


77 


0034 




LD 


(HL),A 


STORE DATA BYTE 


002E 


0D 


0035 




DEC 


C 


COUNT BIT 


002F 


C23B00 


0036 




JP 


NZ.VT3 


DONE WITH BYTE? 


0032 


0E08 


0037 




LD 


C,8 


RESET BITCOUNT 


0034 


23 


0038 




INC 


HL 


MOVE POINTER 


0035 


7C 


0039 




LD 


A,H 


SET UP FOR COMPARE 


0036 


FE10 


0040 




CP 


010H 


AT 4 K BOUNDARY? 


0038 


CA2400 


0041 




JP 


Z.VOT 


YES, REPEAT AD INFINITUM 


003B 


CD4100 0042 ' 


/T3 


CALL DEL 


100 MICROSECOND WAIT 


003E 


C32900 


0043 
0044 




JP 


VT2 


LOOP AGAIN 


0041 


0609 


0045 


DEL 


LD 


B,9 


CALIBRATE CONSTANT FOR ] 


0043 


05 


0046 


D2 


DEC 


B 




0044 


C24300 


0047 




JP 


NZ.D2 


LOOP UNTIL DONE 


0047 


C9 


0048 
0049 




RET 






0048 


00 


0050 
0051 


3UF 


NOP 




START OF BUFFER MEMORY 


0049 


(0000) 


0052 




END 







cy. For example, (l/a)sin(af) is such a 
signal, when a is an arbitrary real 
(nonzero) constant. Thus, if we had 
applied (l/6.5)sin 6.5f to the system 
(instead of just sin 6.5f as in the 
previous example), the output would 
have been a reconstructed waveform 
of both proper frequency and 
amplitude. 

The system of figure 2 is therefore 
limited to reconstruction of signals 
which fall off in amplitude by 
20 dB/decade. Figures 3i, 3j, 3k, and 
31 show what the system does to a 
more complicated signal which meets 
the restriction. The important thing 
to note is that the wave shape (and 
hence the frequency content) of the 
original signal is faithfully repro- 
duced, and the relative amplitudes 
are maintained. 

Speech signals (eg: a voltage 
waveform produced by a microphone 
whose output is linearly proportional 
to pressure) generally have amplitude 
components which drop off as a func- 
tion of frequency by about 20 dB/ 
decade. This is true for both short- 
term (125 ms) and long-term (a 
minute or so) measurements. Hence, 
one would expect the system of figure 
2 to be capable of reproducing fairly 
natural-sounding speech which, in- 
deed, it does. 

Actually, differentiated-clipped 
speech is just as intelligible as 
differentiated-clipped-integrated 
speech (ie: no new information is pro- 
duced by simply integrating the 
bivariate waveform at the com- 
parator output), but it is very 
unpleasant to listen to. Some types of 
music can also be recorded using this 
system, with recognizable melodies 
and harmonies. 

Distortion 

Distortion may come from several 
different locations in this system of 
speech recording and playback. If, 
for example, the input signal does not 
have components which fall off in 
amplitude by exactly 20 dB/decade, 
there is no hope for an "exact" 
playback using the circuit of figure 1. 
This situation arises when several 
persons are speaking simultaneously 
at different levels of loudness. The 
voices tend to mask or distort each 
other. A similar situation occurs 
when one person talks in a noisy en- 
vironment. Another source of distor- 
tion comes from the fact that the 
system can produce only ramp-type 



42 February I'M © BYTE Publications Inc 



waveforms at its output, no matter 
what the input looks like. 

With additional hardware and soft- 
ware, these problems can be greatly 
overcome, resulting in an improve- 
ment in speech quality. If, instead of 
a simple squelch circuit, the slowly 
varying amplitude-envelope signal is 
sampled with an A/D converter, and 
if this data is used to amplitude- 
modulate the constant-level clipped 
speech signal when it is reproduced 
for output, the quality of the signal is 
improved. However, the overall data 
rate required is approximately 
15,000 bps, and requires additional 
hardware. The system of figure 1 is 
about the best we can do in terms of 
simplicity and cost when it comes to 
low-bandwidth speech processing. 

Sample Rates 

If one is to use clipped speech as a 
digital recording technique, distor- 
tion due to a finite sampling rate must 
be considered. Figure 1 shows a 
typical system for recording a 
vocabulary of selected words which 
may later be used for computer voice 
response. Experiments have shown 
that highly intelligible speech can be 
obtained with a sampling rate of 
about 10 kHz. Note that this sam- 
pling rate is an experimental result 
and has nothing to do with the well- 
known sampling theorem, which 
states that the rate of sampling must 
be at least twice the highest frequency 
to be recorded, in order to ensure an 
accurate reproduction. Here we are 
essentially sampling a square wave, 
which is not a band-limited signal. 

To understand why the 10 kHz 
sampling rate is adequate, consider 
the fact that the human ear loses 
resolution at high frequencies. For ex- 
ample, the note A above middle C 
has a fundamental frequency of 440 
Hz. The next note above it (A sharp) 
has a frequency of 440 X 1 \[1 , or ap- 
proximately 466 Hz. The highest A 
on the piano, which is 3 octaves 
above 440 Hz, has a frequency of 
2 3 X440 or approximately 3520 Hz. 
Similarly, the highest A sharp has a 
frequency of 2 3 X 466, about 3729 Hz. 

The difference between 440 Hz and 
466 Hz sounds the same as the dif- 
ference between 3520 Hz and 3729 
Hz, even though the actual frequency 
difference is 26 Hz versus 209 Hz. 
Thus, our ability to resolve frequen- 
cies deteriorates rapidly with increas- 
ing frequency. In the case of clipped 



speech, time quanta of about 0.1 ms 
are adequate and the ear cannot easi- 
ly discern errors introduced in the fre- 
quencies which are reproduced. 
Sampling clipped speech at rates 
much higher than, say, 20 kHz mere- 
ly wastes computer memory while of- 
fering no appreciable improvement in 
speech quality. 

Final Note 

It appears that clipped speech 
techniques can be used in cases where 
a limited-vocabulary computer voice 
response is needed. In terms of 
simplicity, ease of implementation, 
and low cost, it is probably optimal. 
For persons on limited budgets such 
as students, hobbyists, and even pro- 
fessional electrical engineers (who see 
applications for computer speech out- 
put but would have trouble justifying 
a large investment), the clipped- 
speech approach presents an alter- 
native to more complex and costly 
systems. ■ 



References 

1 . Flanagan, J L. Speech Analysis, Syn- 
thesis, and Perception. New York: Academic 
Press Inc, 1965, pages 137 thru 139, 238 thru 
240, and 270 thru 273. 

2. Fletcher, Harvey. "Some Physical 
Characteristics of Speech and Music." The 
Bell System Technical Journal, July 1931, 
pages 349 thru 373. 

3. Graeme, Tobey, and Huelsman. Opera- 
tional Amplifiers. Burr-Brown, McGraw-Hill 
Book Co, 1971, pages 267 thru 268. 

4. Licklider, J C R. "The Intelligibility of 
Amplitude-Dichotomized, Time-Quantized 
Speech Waves." The Journal of the 
Acoustical Society of America, Volume 22, 
Number 6, November 1950, pages 820 thru 
823. 

5. Licklider, J C R, and G A Miller. "The 
Perception of Speech." Handbook of Ex- 
perimental Psychology, pages 1040 thru 
1074. Psychological Abstracts, Volume 25, 
8040, December 1951. 

6. Licklider, J C R and Irwin Pollack. "Effects 
of Differentiation, Integration, and Infinite 
Peak Clipping upon the Intelligibility of 
Speech." The Journal of the Acoustical 
Society of America, Volume 20, Number 1, 
January 1948, pages 42 thru 51. 

7. Young, L L and Jeanette Goodman. "The 
Effects of Peak Clipping on Speech In- 
telligibility in the Presence of a Competing 
Message." IEEE Acoustics, Speech & Signal 
Processing, 1977, pages 216 thru 218. 



Attention 

BOTE 

Readers: 

Would You 

Like To Write For 

onComputing? 

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software and hardware appear- 
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market has increased dramati- 
cally in the past few months. 
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programs and systems, games, 
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and even "homebrew" pro- 
grams created by our readers. 

If you're a good writer, 
onComputing is interested in 
your opinions. We are looking 
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computer jargon, please (unless 
you explain it completely in the 
review). 

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February 1981 © BYTE Publications Inc 43 



Ciarcia's Circuit Cellar 



A Computer-Controlled Tank 



Steve Ciarcia 

POB 582 

Glastonbury CT 06033 



My guess is that when you first 
scanned the title of this article and a 
few of the photos, you immediately 
recognized Milton-Bradley's Big 
Trak. Perhaps it was one of the gifts 
your children received during the 
holidays. 

Big Trak, shown in photo 1, is a 



Copyright © 1981 by Steven A Garcia. 
All rights reserved 



computer-controlled, motorized toy 
tank. Commands to move, to turn, 
and to fire the "photon cannon" are 
programmed by a user (via a keypad) 
into the tank's control system. After 
the user presses the "Go" key, Big 
Trak takes off, executing the stored 
command sequence. 

Big Trak's keypad contains a key 
for each command. Some commands 
are completed with a single key- 



stroke, while other commands re- 
quire multiple keystrokes for the 
entry of parameters. A list of com- 
mand functions appears in table 1. 

Commands may be chained and 
carried out sequentially. For example, 
pressing the sequence: Forward, 2, 
Left, 3, 0, Hold, 1, 0, Fire, 3, Go, 
causes the tank to drive forward 2 
feet, pivot 180°, wait 1 second, and 
then fire three cannon blasts. This se- 




Photo 1: The Big Trak microprocessor-controlled, user-programmable tank, sold by the Milton-Bradley Company. 

44 Febiuaiy 1981 © BYTE Publications Inc 



quence is four commands. Big Trak 
can hold sixteen commands. 

Considering this month's Circuit 
Cellar title and the description thus 
far, you may think this article is 
about Big Trak and the microcom- 
puter control system it employs. You 
are half right. Big Trak is indeed the 
tank mentioned in the title. However, 
the word "Computer" in "Computer- 
Controlled Tank" refers to your per- 
sonal computer, rather than the 
microprocessor inside the tank! 

For a long time I have been in- 
terested in robotics. I have always 
fantasized about building a robot to 
do simple tasks. I am sure that many 
others have similar interests. Unfor- 
tunately, due to the high expense and 
the mechanical expertise required, 
most of us never get beyond the idea 
stage. 

Playing with Big Trak is a tease. It 
is not a robot, nor can it be converted 
into one. However, it has features 
that are fascinating as well as ag- 
gravating for robot-building pro- 
crastinators like myself. Big Trak has 
a control system that memorizes com- 
mands and coordinates a mechanical 
drive. It converts simple keystrokes 
into complex movements combined 
with light and sound effects. 

While the microprocessor program 
that controls the tank is interesting, it 
is the price/performance ratio of the 
mechanism that is impressive. Big 
Trak incorporates a two-wheel/two- 
motor gearbox. The wheels turn syn- 
chronously for forward or backward 
motion and contrariwise for turns. 
Left and right turns are precisely 
definable (to a resolution of 1 part in 
60). This drive mechanism would 
take many hours to fabricate if you 
were building it from scratch. 

For die-hard robotics types, this is 
kid stuff. EXACTLY! But, to some- 
one with just a passing interest, the 
capabilities of this $50 toy are fasci- 
nating. With a little ingenuity, it 
could serve as a test bed for robot en- 
thusiasts on a tight budget. It could 
also serve as a school project combin- 
ing programming and actual control 
of a mechanical device. 

If only it could be linked with a 
larger computer and remotely con- 
trolled! 

This idea sounded like a fun pro- 
ject, so I decided to write an article on 
converting Big Trak to remote con- 
trol. The result is an interface that 
allows complete wireless control of 



the tank's operation from your com- 
puter keyboard. Virtually no modifi- 
cation is required to your computer if 
it already incorporates a serial I/O 
(input/output) port and 300 bps (bits 
per second) modem. 

Writing the control program isn't 
hard. Commands are communicated 
as LPRINT CHR$(X) statements in 
BASIC. (For example, an LPRINT 
CHR$(81) fires the photon cannon.) 
A program which demonstrates this is 
included. (See listing 1.) 

At the other end of the link, a cir- 
cuit is installed in the tank to receive 
control commands from your com- 
puter and simulate the user pressing 
the keypad. This is not a specialized 
interface applicable only to Big Trak; 
the receiver has useful applications 
elsewhere. It is designed in two sec- 



tions: a tank interface specifically for 
this application and a general-use 
wireless receiver/demodulator. The 
receiver/demodulator can easily 
serve as a wireless serial RS-232C ex- 
tension for your computer in other 
applications. Don't care to string 
wires for a printer located in another 
room? Use this receiver interface up 
to 200 yards from the computer. 

All this will be explained in detail, 
but first, back to Big Trak. 

Inside Big Trak 

Big Trak gets its control capability 
from a TI (Texas Instruments) 
TMSlOOO-series 4-bit micropro- 
cessor. This single 28-pin CMOS 
(complementary metal-oxide semi- 
conductor) integrated circuit contains 
programmable user memory, ROM 



Single Entry: 
Test 
Clr 
CIs 
Ck 
Go 



— Tests tank operation by moving and tiring cannon 

— Erase all previous command entries 

— Erase last entry only 

— Execute last command entry immediately 

— Execute complete command sequence 



Multiple Entry: 

Backward/Forward 

Turn (Left/Right) 

Fire 

Hold 

Repeat 



— How far? Enter 1 to 99 feet. 

— How much? Enter 2-digit turn value. 

— How many shots? Enter 1 to 99 shots. 

— How long? Enter 0.1 to 9.9 seconds. 

— How many steps back? Enter 1 to 15. 



Table 1: Summary of commands as entered on Big Trak's keypad. Some commands 
are completed with a single keystroke, while other commands require multiple key- 
strokes (to enter qualifying data, such as how far to travel). The actual Big Trak key- 
pad is shown in photo 3. 








.» .4, 1,11.1 XI. J HUIlJillllJ 

Haifa!* t 




Photo 2: The microprocessor control system inside Big Trak. The 28-pin integrated cir- 
cuit is a TI TMSlOOO-series 4-bit microprocessor. The smaller package is a hex digit 
driver used in this application to power the various tank functions. 



February 1981 © BYTE Publications Die 45 



R8-*- 
R94- 



R10-*- 

GND 

Kl 

KZ 

K4 

K8 — 

INIT 

074- 
064- 



054- 

04 4- 

034- 



"W 



28 
27 
26 
25 
24 
23 
22 
21 
20 
19 
18 
17 
16 
15 



TMS1000/ 
TMS1100 



-»-R7 
-►■R6 
-»-R5 



► R4 
►R3 
►R2 



*-Rl 

»-R0 

•► 9V 

4 OSC 2 

4 0SC1 

»-00 

»-01 



-♦02 



Figure 1: Pin usage of the 77 TMS1000 
4-bit microprocessor. The TMSlOOO-series 
processors all have the same instruction 
set, differing in the number of pins used 
for I/O and in the amount of memory 
contained in the package. 



Pin Name 

K1,K2,K3,K4 
OO thru 07 
RO thru R10 
0SC1, 0SC2 
INIT 


Description 

data input 
data output 
control output 
timing 
power-on reset 


Type 

input 

limited code output 

output 

input (resistor/capacitor) 

input 





PIN 23 



Q Q A A A C 



PIN 8<3~ 



PIN 7<C3~ 



PIN 6<^]- 



>X 

-L 



OUT 



X 



°X 

X 



•x 

X 



=x 

X 



-x 

X 



•X 

X 



X 



•x 

X 



•X 

X 



•X 

X 



•X 

X 



»x 

X 



-X 

X 



-X 

X 



CLS 



°x 

X 



>x 

X 



'X 

-1 



1 



°x 

X 



CLR 



'X 

X 



FIRE 



*x 

X 



°x 

X 



HOLD 



X 

I 



PIN 5<CJ- 



Figure 2: Schematic diagram of the Big Trak's keypad matrix. The column lines are 
connected to the R-series output pins on the TMS1000, and the row lines are connected 
to the K-series input pins. The physical structure of the keypad can be seen in photo 4. 



(read-only memory), and I/O capa- 
bility. The low cost (under $1 in large 
quantities) makes this the product of 
choice for many simple applications 
such as computer games and ap- 
pliance controls. 

The TMS1000 microprocessor 
series is actually a family of fifty-odd 
devices. They all share a common in- 
struction set. The differences are the 
number of I/O pins and the amount 
of on-board memory. The package of 
Big Trak's 28-pin microprocessor, 
shown in photo 2, is marked only 
with a "house" number. It is most 
likely either a TMS1000 or a 
TMS1100. The only difference be- 
tween these two components is the 
amount of memory they contain. The 
TMS1000 has 1 K bytes of ROM and 
32 bytes of programmable memory, 
while the TMS1100 has twice as much 
of each memory. 

As shown in figure 1, the micropro- 
cessor has four dedicated input lines 
and nineteen dedicated output lines 
(OO thru 07 and RO thru RIO). The 
eight data outputs, OO thru 07, are 
wired in an unusual way and can be 
set to only 32 out of the usual 256 



values possible with an 8-bit code. 
This is because the O-series outputs 
receive only the 4-bit values from the 
accumulator and the status flag (1 bit) 
as inputs. The enabled range of the 32 
values (out of the 256) is mask-pro- 
grammed during manufacture of the 



The "wireless ex- 
tension cord" can be 
used with other 
peripheral devices 
besides Big Trak. 



circuitry on the silicon chip. 

The R-series output lines, on the 
other hand, are treated as eleven con- 
trol outputs. Each R output line can 
be set or cleared individually. 

The Big Trak uses these lines to 
read input data from the keypad, gen- 
erate sound effects, light up the 
"photon cannon," and coordinate the 
operation of the two motors. 

Because the TMS1000 is a low- 



power device (about 90 mW), it can- 
not directly drive a motor. A second 
integrated circuit (an SN75494) and a 
few transistors facilitate the connec- 
tion. The 75494 is a hex digit driver 
primarily intended to interface 
CMOS devices to common-cathode- 
configured LEDs (light-emitting 
diodes). While the tank uses no LEDs, 
the 150 mA drive-current capability 
of the 75494 makes it particularly 
suitable in this application. 

Connection of the keypad (shown 
in photo 3) to the microprocessor is 
straightforward. The keypad is ac- 
tually a matrix of processor I/O lines. 
Outputs RO thru R5 and inputs Kl, 
K2, K4, and K8 form a 4 by 6 matrix 
(only twenty-three keys are func- 
tional — the In key has no contacts) as 
shown in figure 2. The K signals are 
the rows, and the R signals are the 
columns. 

Such a keypad operates on a 
scanned-matrix principle. The pro- 
cessor alternately places a signal on 
each R line and reads the four inputs 
for any completed circuit (which 
shows a key being pressed). Entering 
a command, therefore, is simply a 



46 February 19S1 © BYTE Publications Inc 



The Big Trak can 

serve as a test bed for 

robot enthusiasts on a 

tight budget. 



process of shorting one of the cross 
points of the matrix. 

The keypad has no springs, mag- 
nets, or raised buttons. It is nothing 
more than two photo-etched plastic 
sheets with conductive traces, 
separated by a thin insulator. At the 
cross points of the matrix, the in- 
sulator has a cutout. Any pressure on 
the keypad surface over this point 
flexes the plastic and shorts the two 
contacts, completing the circuit. 
Photo 4 shows the structure of the 
keypad. 

Practically speaking, any connec- 
tion between a column and a row of 
the matrix will be perceived as a valid 
data input to the processor. For ex- 
ample, if you use a clip lead to con- 
nect pins 8 and 26 on the processor 
package, it will accept this as a Go 
command and commence operation. 
This concept is the premise of my 
remote-control circuit. 

External Keyboard Control 

Remote control of Big Trak starts 
with an interface that attaches to the 
processor and functions in place of 
the keypad. Figure 3 shows the sche- 
matic diagram of a circuit that does 
this. The prototype is shown installed 
over the processor board in the tank. 
(See photo 5.) Its location with 
respect to the tank layout is better 
shown in photo 6. 

The integrated circuits IC2 and IC3 
are 8-channel type-CD4051 CMOS 
multiplexers. The 6 matrix column 
lines are attached to IC2, and the 4 
row lines are connected to IC3. The 
selection of 1 of the 6 column lines 
and 1 of the 4 row lines is determined 
by the address-input lines A, B, and C 
on each integrated circuit. A total of 5 
address bits are required. While a six- 
conductor cable (5 bits of data and 
ground) strung between the computer 
and the tank for parallel communica- 
tions would work, it is hardly effi- 
cient as remote control. Serial com- 
munication is better, for a number of 
reasons. 

The components ICl, IC4, and IC5 
function as a 300 bps serial-to-parallel 




Photo 3: Commands are entered into Big Irak's memory through this keypad on the 
top of the tank. 



converter which operates on 9 V 
(note the use of the General Instru- 
ment AY-3-1014A UART, a universal 
asynchronous receiver/ transmitter). 
Data comes into pin 20 of IC3 at 300 
bps where it is reconverted to parallel 
format. Bits thru 2 (DO thru D2) go 
to IC2, and bits 4 and 5 (D4 and D5) 
go to IC3. The choice is not arbitrary. 
By selecting these particular bits as 
the address inputs, the CMOS switch- 
es can be set by binary codes that cor- 
respond to ASCII (American Stan- 
dard Code for Information Inter- 
change) characters. This makes the 



interface more flexible, since its func- 
tions can be exercised directly 
through characters output by use of 
the CHR$(X) function in the BASIC 
language. The necessary codes are 
common, printable characters and 
will not interfere with machine opera- 
tion. (In some BASICs, the CHR$(X) 
function can cause strange things to 
occur, depending upon the value of 
X. In my computer system, sending a 
CHR$(127) clears the screen and 
resets the cursor.) Choosing printable 
codes also aids troubleshooting. 
Table 2 lists the twenty-three codes 



February 1981 © BYTE Publications Inc 47 



used in this interface. For example, 
sending an "R" (with the output state- 
ment LPRINT CHR$(82)) tells the 
tank to make a right turn. 

Oscillator IC5 (a 555 timer) is 
tuned for 4800 Hz. This sets the com- 
munication data rate at 300 bps. A 
rate of 110 bps is set by changing the 
oscillator frequency to 1760 Hz. 

Operation is straightforward. The 
UART is hard-wired for 8 bits of 



data, no parity bit, and 1 stop bit. 
When a character is received, the 
data-output line becomes active and 
the DAV (data available) line goes 
high. One section of IC4 s erves to 
delay the reset pulse to the RDAV 
(reset data available) input. This pro- 
duces a 10 ms strobe signal which 
closes the CMOS switches. (While the 
data rate may be 300 bps, time must 
be allotted between characters to 




Photo 4: A rear view of the keypad, showing its construction. The keypad consists of 
two plastic sheets containing photo-etched conductors separated by a layer of insula- 
tion. At the locations of the function keys, the insulation has a circular cutout through 
which the two conductive layers can touch when pressure is applied. 




Photo 5: The prototype of the Big Trak control interface of figure 3. It is mounted on 
top of the tank's processor board and is powered by the tank's 9 V battery. The inter- 
face contains a 300 bps serial-to-parallel converter which directs the operation of the 
CMOS switches attached across the keypad matrix. 



allow the tank control system to re- 
spond. The effective data rate is more 
like five commands per second.) 
Whatever points were addressed on 
IC2 and IC3 will be electrically con- 
nected. The tank will then either store 
or execute the command, depending 
upon what it is. 

Functionally speaking, you could 
stop right now. If you don't mind a 
two-wire cord running from your 
computer to the tank, you can con- 
trol it with just the circuit so far 
described. Simply set your serial out- 
put port at 300 bps and feed its signals 
directly to pin 9 of IC4 in the inter- 
face. This, in fact, was the way I had 
to test the circuit before I went on to 
the next step. 

Constructing a "Wireless 
Extension Cord" 

The next step is, of course, the real 
fun part of this project. Since we can 
now command the tank through 
serial-character transmissions, it is 
only natural to consider eliminating 
the wire and using wireless com- 
munication. 

Let's take stock. We have a tank 
that for all practical purposes is 
remote-controlled. All we have to do 
is send TTL (transistor-transistor 
logic)- or CMOS-level serial char- 
acters to it. These characters, in turn, 
come from BASIC LPRINT CHR$(X) 
statements, the output of which is 
transmitted serially. On the computer 
side, we have a serial output, and on 
the tank side we have a serial input. 
Connecting the two requires an "ex- 
tension cord," either physical or 
ethereal. 

One method, shown in the block 
diagram of figure 4, uses radio trans- 
mission. The approach is not as 
strange as it might initially seem. The 
serial output from your computer is 
FSK (frequency-shift keyed) modu- 
lated and transmitted. Somewhere at 
a remote location, a receiver picks up 
this transmission and demodulates it. 
The reconstructed serial data is fed in- 
to the remote device, in our case, the 
Big Trak control interface. 

Please note the following: because 
this interface uses standard serial- 
data rates and voltage levels, any 
wireless communication device we 
design to accommodate computer/ 
Big Trak communication will also 
work for any other similar-rate com- 
munication. The computer doesn't 
know whether it is "talking" to a tank 



48 February 1981 © BYTE Publications Inc 



Meet ttie Tiger with 
a biager bite. 



Introducing the remarkable 132-column 
Paper Tiger™ 560. The first full-width matrix 
printer to give you fully formed characters 
for a low $1695.* 

The new 560 features a staggered nine- 
wire ballistic type print head that overlaps 
dots in both horizontal and vertical planes. 
It bi-directionally prints up to 150 dense, text 
quality characters per second. 

The 560 also features a reliable cartridge 
ribbon that lasts up to four times as long 



presents a breakthrough in matrix printini 
ering the user excellent print quality wit! 
ce of a matrix printer. Employing a uniq 
red column" head manufactured by Integr 
creates high quality printouts by overla 



Paper Tiger 560 Print Sample 

as spool and cassette ribbons, separate 
heavy-duty stepper motors to drive the print 
head and advance the paper, plus true 
tractor feed. 

And famous Paper Tiger performance 
comes with every new 560. Like fixed or 
proportionately spaced text, programmable 
tabbing and business forms control, auto- 
matic text justification, print formats to 220 



columns, parallel and serial interfaces, self- 
diagnostics, and more. All inside the most 
compact printer of its kind. 

Need more stripes? Dotplot ,™ our high- 
resolution raster graphics package, is stan- 
dard on every 560. 

For data processing, word processing 
and small business applications, this is your 
Tiger. The business-sized Paper Tiger™ 560. 

It's a Tiger you can count on. 

Call TOLL FREE 800-258-1386 (In New 
Hampshire, Alaska and Hawaii, call 
603-673-9100.) Or write: Integral Data 
Systems, Inc., Milford, NH 03055. 




Tiger 560 

■Up) Jlntegral Data Systems, Inc. 



'Suggested U.S. retail price. 



Circle 27 on inquiry card. 



"PIN 21^} 



5.1 K 

YPICAL FOR 6) 




CONNECTIONS 
TO BIG TRAK 
TMS 1000 
M ICROPROCESSOR 




eO 



10K 



+9V 

A 



'20K 



;0.022/iF 
MYLAR 



DIS 



RESET 

IC5 

OUT 
NE555 



TSLD 



TRIG 



4800 Hz 



(300bps) 



Number 

IC1 
IC2 

IC3 
IC4 
IC5 



Type 

AY-3-1014A 

CD4051 

CD4051 

CD4049 

NE555 



12 



11 



10 



19 



IC1 

AY-3-1014A 

UART 



CS 

NP 

NB2 

NB1 

RDE 
SWE 
RESET 
TSB 
EPS 

SI 
RDAV 



37 



16 



21 



18 



rft 



IC4 
CD4049 



>0.1^iF 



I-9V 
A 



38 



36 



+ 9V 

1 

16 
16 
1 



9V 

t 



+ 9V 



100K 
AAft 



GND 

3 

7,8 

7,8 

8 
1 



A 



SERIAL DATA 
INPUT FROM 
FIGURE 7 



Figure 3: Schematic diagram of the Big Trak remote-control interface. This circuit is installed inside the tank, replacing the function 
of the manual keypad. The address-input lines on each of the two CD4051 8-channel multiplexers select the rows and columns of the 
keypad matrix. 

The AY -3-1014 A UART is a product of General Instrument Corporation, Microelectronics Division, 600 W John St, Hicksville NY 
11802. 



COMPUTER 
TTL/RS- 232C 
SERIAL OUTPUT 



MODULATOR 



ANTENNA 



V^V 



TRANSMITTER 





SERIAL INPUT 
TO REMOTE 
DEVICE 
(BIG TRAK) 


ANTENNA 




i 




RECEIVER 













Figure 4: Conceptual block diagram of a typical wireless communications link. 



or to a remote printer. The "wireless 
extension cord" depicted in figure 5 
can just as easily be attached between 
the computer and any output 
peripheral device. 

Figure 5 outlines a simple way to 
accomplish this communication. At 



the computer, an FSK modulator con- 
verts the 1 and levels to 2025 Hz and 
2225 Hz tones. These tones are trans- 
mitted using an inexpensive 49.86 
MHz walkie-talkie. At the receiving 
end (in this case, the Big Trak), 
another walkie-talkie receives the 



tones and a demodulator reconverts 
the tones to logic levels which are fed 
to the UART/control interface. 

Figure 6 is a schematic diagram of 
an answer-type modem modulator. 
The assembled circuit is shown in 
photo 7. Serial data from the com- 
puter is fed into pin 1 of IC2, as 
shown. A logic 1 input produces a 
2225 Hz tone, and a logic input pro- 
duces a 2025 Hz tone. These tones are 
amplified by IC3 and are directly fed 
to the walkie-talkie transmitter, 
through a connection across its 
speaker. 

Figure 7 is a diagram of the circuit 
required at the receiving end. It con- 
sists of an originate-type modem de- 
modulator and a walkie-talkie 
receiver. The guts of the walkie-talkie 
are removed from its case and 
mounted in the same enclosure with 



50 February 1981 © BYTE Publications Inc 




At $7951 how tough can 
these new Tigers be? 



Introducing the new Paper Tiger™ 
445 with the most rugged printing 
mechanism ever put in a low-cost 
matrix printer. 

The 445 comes with a reliable ballis- 
tic-type print head and an advanced 
cartridge ribbon that lasts four times 
longer than many cassette or spool 
ribbons. Two separate heavy duty 
motors drive the print head 
and advance the paper. Plus you get 
true tractor paper feed. 

And the new 445 gives you the per- 
formance you expect from the Paper 
Tiger family of printers . You can soft- 
ware-select character sizes, print 
80- and 132-column formats, adjust 
paper width and length, even gen- 
erate six-part business forms. All at 
unidirectional print speeds to 198 
characters per second. 



Need more stripes? Specify DotPlot™, 
a sophisticated raster graphics option. 

If you've got an Apple**, TRS-80*** 
or other personal computer, get your 
paws on the tough new Paper Tiger™ 
445 from IDS. 

The people who invented low-cost 
matrix printing just growled. 

Call TOLL FREE 800-258-1386 (in 
New Hampshire, Alaska and Hawaii, 
call 603-673-9100.) 
Or write: 
Integral Data 
Systems, Inc., 
Milford, New 
Hampshire 
03055. 



HI 



KX33 




Tiger 445 

w£p) J Integral Data Systems, Inc. 




Circle 28 on inquiry card 



'Suggested U.S. retail price. 
"Apple is a trademark of Apple Computer Inc. 
"TRS-80 is a trademark of Radio Shack, a division of Tandy Corp. 



the modem board. Photo 9 shows the 
receiver mounted in the bottom of the 
box. The modem board is mounted 
on stand-offs over the receiver, and 
batteries are placed along the edge 
and under the board, as shown in 
photo 10. 

The audio output of the walkie- 
talkie is tapped from speaker leads; a 
10-ohm resistor should be substituted 
for the speaker if you don't wish to 
hear the tones. This audio signal is 
connected to the modem preamplifier 
input. It is next sent through a band- 



pass filter and limiter, which max- 
imizes the signal level yet keeps it 
under the saturation point of the de- 
modulator. The demodulator, IC3, is 
an XR2211 monolithic PLL (phase- 
locked loop). It is set to work at 2025 
and 2225 Hz. The output of the de- 
modulator is a logic signal that is 
compatible with the UART in the 
tank controller. 

The basic circuits shown in figure 6 
and 7 were originally presented in the 
Circuit Cellar article titled "A Build- 
It-Yourself Modem for Under $50" 




Photo 6: Big Trak undergoing modification. The interface circuit of figure 3 may be 
seen inside, in front of the keypad. 




(BYTE, August 1980, page 22). I refer 
you to that article for a more com- 
plete explanation of modem com- 
munication. (See also "BYTE's Bugs," 
BYTE, October 1980, page 332, and 
November 1980, page 112.) 

Wireless remote control in an auto- 
mated-house application was dis- 
cussed in "Handheld Remote Control 
for Your Computerized Home," 
BYTE, July 1980, page 22. 

The printed-circuit boards shown 
in photos 7 and 10 are the production 
modem boards originally offered as a 
kit with components for those people 
interested in constructing their own 
modems from the August article. 
These circuit boards are still available 
and were used to construct the inter- 
face described in this article. A text 
box at the end of this article tells how 
to order one of these boards. 

The completed interface is a fairly 
neat package. While it is large in com- 
parison to the five-integrated-circuit 
assembly inside the tank, it can still 
be toted along behind Big Trak by us- 
ing the Big Trak Transport, the tank's 
cargo trailer. A cable and jack con- 
nect the receiver to the controller in- 




Photo 7: The modulator section of an answer-type modem. The serial data output from 
the computer is modulated according to an FSK scheme into audio tones with frequen- 
cies of 2025 and 2225 Hz. 



Photo 8: The output of the modem 
modulator is connected by a cable to this 
walkie-talkie (a Radio Shack number 
60-4001) for transmission to the receiver 
on the Big Trak. The connection to the 
transmitter section of the walkie-talkie is 
made across the speaker terminals, with a 
10-ohm resistor inserted in the circuit in 
place of the speaker. A phono jack in- 
stalled on the front of the walkie-talkie 
facilitates the connection. 



52 February 1981 © BYTE Publications Inc 



Circle 29 on Inquiry card. 




BRAIN 



Once in a great while someone comes along 
with a simple improvement for an already great 
product. Take our SuperBrain, for example. Really a 
simple concept. A high-powered, low cost micro- 
computer packaged in an attractive desk top 
cabinet. So how do you improve on that? 

WE DID IT... 

It wasn't enough that our SuperBrain had 
such standard features as twin double density 
5%" drives with over 300,000 bytes of disk 
storage. A full 32K of dynamic RAM - expandable 
to 64K in seconds. A CP/M* Disk Operating 
System which assures compatibility to literally 
hundreds of application packages presently availa- 
ble. A crisp, 12" non-glare screen with a full 24 
line by 80 column display. A full ASCII keyboard 
with a separate keypad and individual cursor 
control keys. Twin RS232C serial ports for fast 
and easy connection to a modem and/or a printer. 
And, dual Z80 processors which operate at 4 MHZ 
to insure lightning-fast program execution. No, it 
wasn't enough. So we made it better. 

ANNOUNCING SUPERBRAIN QD... 

Our new OD model has all of the features of 
our phenomenally popular SuperBrain with the 
addition of double-sided disk drives and an extra 
32K of dynamic RAM. So, for only a modest in- 
crease in price, you can order your next SuperBrain 
with more than twice the disk and memory storage 
capability. But, best of all, the new OD model has 
the same tough, rugged construction and 
exceptional quality that made our SuperBrain 
such a success. 





HOW DID WE DO IT? 

The secret of SuperBrain OD's incredible disk 
storage lies within our new double-density double- 
sided disk drives. A total of nearly 720,000 bytes 
of data are formatted on two specially designed 
5%" drives. And that's more than enough to get 
you started with most serious small business 
applications. And SuperBrain OD's standard 64K of 
dynamic RAM will handle even the most complicat- 
ed programming tasks. 

Of course, if you're into megabytes instead of 
kilobytes, you may think neither SuperBrain is right 
for you. Not so! Intertec offers 20-96 megabytes of 
hard-disk storage which connects in seconds to 
either the SuperBrain or SuperBrain OD. So, your 
original investment is always protected. As you 
grow. No matter how much your needs expand. 



BUT IS IT RELIABLE? 

Our best salesmen are our present users. Not 
only have SuperBrain users been impressed with 
the inherent reliability of the system, they tell us 
that no other microcomputer system available 
today offers such a unique modular design con- 
cept. Just about the only tool required to easily 



maintain the system is a common screwdriver. And 
Intertec's total commitment to product service and 
customer support, with service outlets in most 
major cities, insures your original investment will 
be a valuable one for many years to come. 

THE DECISION IS YOURS. 

Whether your next SuperBrain is a regular 
model or our OD version, you will have the 
satisfaction of knowing you purchased what is 
becoming one of the world's most popular micro- 
computer systems. And regardless of which model 
you choose, you'll probably never outgrow it be- 
cause you can keep expanding it. 

So, call or write us today for more infor- 
mation. Intertec systems are distributed worldwide 
and may be available in your area now. 



3 



_ NTE3TEC 

Cdata 
s systems. 



2300 Broad River Rd„ Columbia, SC 29210 
(803) 798-9100 TWX: 810-666-2115 




* of DiQiialReseaith. Inc 



7antenna 

computer interface 




1 








V 










TRANSMITTER 
(WALKIE -TALKIE 
IN TRANSMIT 
MODE) 




ANSWER 
MODEM 
MODULATOR 
(2025-2Z25 Hz) 




300 bps 
SERIAL 
INTERFACE 




COMPUTER 

RUNNING 

BASIC 











ANTENNA 




WIRELESS EXTENSION CORD 



TANK INTERFACE 



RECEIVER 
(WALKIE -TALKIE 
IN RECEIVE 
MODE) 



•N 


t 






■v 






ORIGINATE 

MODEM 

DEMODULATOR 


SERIAL-TO- 
PARALLEL 
CONVERTER 


CMOS 
SWITCHES 


TANK 
KEYBOARD 









Figure 5: Block diagram of the wireless remote-control system described in this article. FSK modulation is employed along with inex- 
pensive walkie-talkies to create a "wireless extension cord. " 



ici 

NE567 



o.ooi^f; 



>10K 



300bps 

SERIAL [Z> 4— (I 

INPUT 



' 2 a p-w^ — (-4 



1 

r 



30 K 




1M 

-wv- 



2.2M 
-A/W, — 



33pF 



mD 8- 



lOaF 

^lOOK 
— Jt WW- 



IC2 
CD4011 



0.01/iF ; 



• 0.01>iF 



"X\H 

10K 
VOLUME 



m m 




220/iF 



o-vf; 



ion • 



ion 



V 



w 



WALKIE- 
TALKIE 
SPEAKER 



m 



rft 



2N2222 



Number 

IC1 
IC2 
IC3 



Type 

NE567 

CD4011 

LM386 



+5V GND 



4 

14 

6 



Figure 6: Schematic diagram of the modulator section of an answer-type modem. The assembled circuit is shown in photo 7. 

In this FSK-modulation scheme, a logic 1 input produces an output frequency of 2225 Hz, while a logic produces an output fre- 
quency of 2025 Hz. The output is connected across the speaker (which also serves as a microphone) in the walkie-talkie, which is con- 
nected to the transmitter section. Capacitors marked with an asterisk (*) should be Mylar type parts. 



terface. The combination 
trailer is shown in photo 11. 



tank/ 



Programming Big Trak from Your 
Computer Keyboard 

Now that you have a remote- 
controlled tank, you have to write a 
suitable control program. The com- 
plexity of the program depends upon 
the level of sophistication you desire. 
The interface was designed for simple 
interaction, and it doesn't require 
much. Complete direction can be ac- 



complished with as little as the 
following BASIC program: 

100 INPUT A 

110 LPRINT CHR$(A); 

120 GOTO 100 

In this program, the value of the 
variable A should be one of the 23 
decimal values listed in table 2. The 
operator must keep track of the entry 
sequence, and Big Trak and the com- 
munication link must be powered at 



all times, because commands are 
entered singly and stored only in the 
tank's control system. 

A much more sophisticated BASIC 
program is shown in listing 1. This 
program allows the operator to 
assemble a command sequence off- 
line with functional entries (Hold, 
Fire, etc) rather than coded inputs. In 
addition, the time needed to develop 
a command sequence becomes less of 
a problem, since power to the tank 

Text continued on page 58 



54 February 1981 © BYTE Publications Inc. 



Circle 30 on Inquiry card. 



Listing 1: A program in BASH ' tiuit ttlhnvs the operator to assemble a Big Trak com- 
mand sequence using functional entries. The command sequence is stored within the 
host computer and is transmitted in its entirety to tiie Big Trak when the operator gives 
the Go command. 



100 
110 
120 
130 
140 
150 
160 
170 
180 
190 
200 
210 
220 
230 
240 
250 
260 
270 
280 
290 
300 
310 
320 
330 
340 
350 
360 
370 
380 
390 
400 
410 
420 
430 
440 
450 
460 
470 
480 
490 
500 
510 
520 
530 
540 
550 
560 
570 
580 
590 
600 
610 
620 
630 
640 
650 
660 
670 
680 
690 
700 
710 
720 
730 
740 
750 
760 
770 
780 
790 
800 
810 
820 
830 
840 
850 
860 
870 
880 
890 
900 
910 
920 
930 
940 



REM ************ BIG TKAK HFIMOTE CONTROL PROGRAM ********** 
REM 
REM 
REM 

REM Clear enough memory space for possible 16 command sequence 
FOR Q = 25000 TO 25048 :POKE Q,u :NEXT Q :REM Clear Memory Table 
REM 

REM Load conversion tabic for ASCII 0-9 to tank code 
DATA 38,53,3 7,8 5,52,3 6,84,51,35,83 
FOR W=0 TO 9: READ B(W): NEXT W 
REM 
REM 

PRINT:PRINT:PRINT:PRINT"COMPUTERIZED REMOTE CONTROL" : PRINT 
K=0 :REM Reset Command Counter 

S=0:T=25000: POKE T,65: T=T+ 1 :REM Set first code in table 
REM it clear code 

PRINT"Command list to be repeated each time (Y or N)";: INPUT C$ 
IF CS="Y" THEN C = l ELSE C=0 :GOSUB 990 :GOTO 300 
REM 
REM 

IF C=l THEN GOSUB 990 ELSE GOTO 310 
PRINT:PRINT"Command" ;: INPUT AS 
IF A$="M" THEN GOTO 440 
C" THEN GOTO 600 
THEN GOTO 650 
IF A$="R" THEN GOTO 720 
IF A$="T" THEN GOTO 760 
IF A$="F" THEN GOTO 820 
IF A$="D" THEN GOTO 890 
IF A$="G" THEN GOTO 920 
IF A$="L" THEN GOTO 1290 
GOTO 310 
REM 

REM Move Command 

PRINT" (F)orward, (B)ackward, (L) eft, or (R) ight" 
IF B$="F" THEN X = 33 :COTO 500 

GOTO 500 

GOTO 550 



IF A$ = 
IF A$="H" 



: INPUT B$ 



IF B$="B" 
IF B$="L" 



THEN X=34 
THEN X=50 



IF B$="R" THEN X=82 :GOTO 550 

GOTO 300 

PRINT"How many feet (1 to 99)";:INPUT Ql 

IF Q1<=0 THEN 500 

IF Ql>99 THEN 500 

GOSUB 9 80 

GOSUB 1090: GOTO 300 

PRINT"Turn how many degrees (0 to 360)";:INPUT Ql :Q1=INT ( (Ql/360) *60) 

GOSUB 980 

GOSUB 1090 :GOTO 300 

REM 

REM Clear Command 

K=0 :S=0 :T=25000 :FOR Q=25000 TO 25048 : POKE Q,0 :NEXT Q 

PRINT"Stored sequence cleared Start Again" :POKE T,65 :T=T+1 

GOSUB 990 :GOTO 310 
REM 

REM Hold Command 

X=49 :PRINT"Hold how many seconds (total times .lsec) " ; :INPUT Ql 

IF Q1<=0 THEN 650 

IF Ql>99 THEN 650 

GOSUB 980 

GOSUB 1090 :GOTO 300 

REM 

REM Repeat Command 

X=67 :PRINT"Repeat how many steps" ;: INPUT Ql :GOSUB 980 

GOSUB 1090 : GOTO 300 

REM 

REM Test Command 

IF T<=25001 THEN 770 ELSE 790 

LPRINT CHR$(68) ; :PRINT"TEST COMMAND TRANSMITTED" 

GOSUB 990 :GOTO 310 

PRINT:PRINT"CAN NOT EXECUTE EXCEPT AS FIRST COMMAND" : GOTO 300 

REM 

REM Fire Command 

X=81 :PRINT"How many shots (1 to 99)";:INPUT Ql 

IF Q1<=0 THEN 820 

IF Ql>99 THEN 820 

GOSUB 980 

GOSUB 1090 :GOTO 300 

REM 

REM Dump (OUT) Command 

X=86 :GOSUB 1090 :GOTO 300 
REM 

REM Command Transmitter 

X=70 :PRINT"COMMAND CONTROL SEQUENCE IS BEING TRANSMITTED TO TANK" 

PRINT :PRINT 

GOSUB 1200 Listing 1 continued on page 58 



SNAPP II EXTENDED DASIC A family of en- 
hancements to the Model II DASIC interpreter. 
Part of the package originated with the best of 
APPARAT, INC.'s thoughts in implementing 
NEWDOS DASIC. The system is written entirely in 
machine language for SUPER FAST execution. 
The extensions are fully integrated into Model II 
DASIC, and require NO user Memory, and NO 
user disk space. The package is made up of the 
following six modules, each of which may be 
purchased separately; 

XDASIC — Six single key stroke commands to list 
the first, last, previous, next, or current program 
line, or to edit the current line. Includes quick 
woy to recover DASIC program following a NEW 
or system or accidental re-boot. Ten single 
character abbreviations for frequently used 
commands: AUTO, CLS, DELETE, EDIT, KILL, 
LIST, MERGE, NEW, LUST, and SYSTEM. $40.00 
XREF — A powerful cross-reference facility with 
output to display and/or printer. Trace a vari- 
able through the code. Determine easily if a 
variable is in use. $40.00 

XDUMP — Permits the programmer to display 
and/or print the value of any or all program 
variables. Identifies the variable type for all 
variables. Each element of any array is listed 
separately. $40.00 

XRENUM — An enhanced program line renum- 
bering facility which allows specification of on 
upper limit of the block of lines to be renum- 
bered, supports relocation of renumbered 
blocks of code, and supports duplication of 
blocks of code. $40.00 

XFIND — A cross reference facility for key words 
and character strings, also includes global re- 
placement of keywords. $40.00 
XCOMPRESS — Compress your DASIC programs 
to an absolute minimum. Removes extraneous 
information; merge lines; even deletes state- 
ments which could nor be executed. Typically 
saves 30-40% space even for programs with- 
out REM statements! Also results in 7-10% im- 
provement in execution speed. $40.00 
ENTIRE PACKAGE ONLY $200.00 



6160 Corporate Pork Dr. 
Cincinnati, Ohio 45242 

, Coll Toll Free = 

1 - 800 - 543-4628 Li'J 
Ohio residents 
coll collect (513)891-4496 

All products now available to run with TRSDOS 2.0 
TRS-80 is o trademark of the Radio Shack 
division of Tandy Corporation. 

Now available for Model III 



February 19S1 © BYTE Publications Inc 55 



Introducing 7 data- shield- 
ing improvements from 
Verbatim for greater disk 
durability, longer data life. 

Improvements to protect 
your data from head-to-disk 
abrasion. Improvements to 
shield your data against loss 
due to environmental condi- 
tions. Improvements that'll 
deliver a longer lifetime of 
trouble-free data recording, 
storage and retrieval than 
ever before possible. 

It's all made possible 
by Verbatim, with these 
improvements: 

1. A longer-lasting lubri- 
cant. Our new lubricant is 
more resistant to diffusion, to 
protect against data-destroy- 
ing head-to-disk contact. 

2. An improved liner. 
Our new liner cleans and 



removes debris better. It also 
enables more lubricant to 
reach the recording head, 
protecting against head wear. 

3. A thicker, more dura- 
ble coating. Our disks have 

a more uniform oxide coating 
for more adhesive and co- 
hesive strength. We've also 
made it thicker; providing 
10% more protective lubri- 
cant and an optimized signal 
resolution for the new record- 
ing heads. >. 

4. Advanced polishing^ 
techniques. Our burnishing 
makes our disks uniformly 
smooth, for better data trans- 
fer, less head wear. 

5. Reinforcing hub rings. 
All Verbatim disks are avail- 
able with hub rings to aid in 
registration, eliminate slip- 
page, reduce errors, and give 



DD32-4000-W3 



Datalife 



\ 



r O 




c 1980 Verbatim Corporation 



formance of a lifetime! 




better alignment repeatability. 

6. Testing standards that 
go far beyond industry stand- 
ards. Every Verbatim disk 
meets or exceeds the most 
demanding of IBM, Shugart, 
ANSI, ECMA and ISO stand- 
ards -because we insist on 
Verbatim being the industry 
standard of excellence. 

We analyze raw materials 
down to their molecular con- 
tent. We subject every coating 
batch to more than 70 chemi- 
cal, magnetic and electrical 
tests. Two separate test groups 
employ life-cycle tests using 
more than 400 disk drives 
from every manufacturer. And 
we conduct "worst case" test- 
ing of every bit of every byte 
of every track of every single 
disk. All to insure that Verba- 
tim disks always pass the ulti- 



mate test: satisfying you. 
7. A 100% Error-Free 
Certification that means 
more than just " 100% error- 
free" Our certification isn't 
based on random sampling, 
or statistical averaging. Rather, 
it's based on extensively test- 
ing every single disk. So we 
can state that our disks really 
are 100% error-free, and back 
it up with a one year warranty. 



"Try new Verbatim for the 
performance of a lifetime! 







m 



We play it back, Verbatim! 



Circle 31 on inquiry card. 



Circle 32 on inquiry card. 




MICROPROCESSOR 
CROSS PASCAL RUN- 
NING ON ALL PDP-11' 
LSI-11 SYSTEMS 

WRITTEN IN MACRO- 
II SYMBOLIC P-CODE 
OUTPUT. . . USER- 
MODIFYABLEAND . . . 

LOW COST !!! 



TARGET 


MICROPROCESSORS 


8085 


6809 


8048 


68000 


Z80 


Z8000 


9900 


8086 


6500 


PDP-11 


6800 





OPERATING SYSTEMS 

UNIX 

RT-11 

RSTS 

RSX-11D 

RSX-11M 

RSX-11M-PLUS 

IAS 




ALSO FROM 
SYSTEM-KONTAKT 



• DOWN LOADERS 
SIMULATORS 
CROSS ASSEMBLERS 

SYSTEM-KONTAKT, Inc. 

6 Preston Court • Bedford. MA 01 730 U.S.A. 
(617) 275-2333 



COMMANDS 


: " 




(F) ire" 




(D)ump" 




(G)o" 




(D) ump" 


NT" 


(T)est" 



Listing 1 continued: 

950 PRINT :PRINT"Retransmit Same Control Sequence (Y or N)",:INPUTQ$ 

960 IF Q$="Y" THEN LPRINT CHR$(70);: GOTO 920 

970 IF Q$="N" THEN 220 ELSE 950 

980 A1=INT(Q1/10) :A=Q1-A1*10 : RETURN 

9 90 REM 

1000 PRINT" 

1010 PRINT" (M)ove 

1020 PRINT" (C)lear 

1030 PRINT" (H)old 

1040 PRINT" (R)epeat 

1050 IF T<=25001 THEN PRINT" 

1060 RETURN 

1070 REM 

1080 REM Store Command Code in Memory Table 

1090 POKE T,X :T=T+1:K=K+1 

1100 IF A+A1=0 THEN RETURN 

1110 IF A1=0 THEN 1130 

1120 POKE T,B(A1) :T=T+1 

1130 POKE T,B(A) :T=T+1 

1140 PRINT" Command Stored"; 

1150 IF K>=15 THEN GOTO 1160 ELSE 1170 

1160 PRINT :PRINT"NEXT COMMAND MUST BE GO !" : RETURN 

1170 RETURN 

1180 REM 

1190 REM LPRINT Command Sequence from Memory Table 

1200 POKE T,X 

1210 FOR E=25000 TO T 

1220 D1=PEEK(E) :LPRINT CHR$(D1); 

1230 FOR C=0 TO 100: NEXT C 

1240 NEXT E 

1250 PRINT"TRANSMISSION COMPLETE" 

1260 RETURN 

1270 REM 

1280 REM Display codes stored in memory table 

1290 FOR N=25000 TO 25048 :PRINT PEEK(N);" ";:NEXT N 

1300 GOTO 300 



Command Name 


ASCII Character 


Hexadecimal Code 


Dec 


mal Code 


Forward 




! 




21 




33 


Backward 




" 




22 




34 


Right 




R 




52 




82 


Left 




2 




32 




50 


Clear (all) 




A 




41 




65 


Clear (last) 




B 




42 




66 


Hold 




1 




31 




49 


Repeat 




C 




43 




67 


Check 




E 




45 




69 


Fire 




Q 




51 




81 


Out 




V 




56 




86 


Test 




D 




44 




68 


Go 




F 




46 




70 







& 




26 




38 


1 




5 




35 




53 


2 




% 




25 




37 


3 




U 




55 




85 


4 




4 




34 




52 


5 




$ 




24 




36 


6 




T 




54 




84 


7 




3 




33 




51 


8 




# 




23 




35 


9 




S 




53 




83 


Table 2: Correspondence 


of ASCII characters 


to the twenty-th 


ree Big 


Trak corn- 


mand codes. The decimal 


values of the ASCII characters are sen 


t to the 


transmitter 


using the BASIC statement LPRINT CHR$(X). 









Text continued from page 54: 

and communication interface need to 
be turned on only when the sequence 
is to be executed. The Go command 
transmits the entire repertoire to the 
tank in one stream of data. 

The data sent to the tank can in fact 
be seen in the sample run of listing 2. I 
used the same serial port designated 
for the wireless communications link 
to list the program. You'll note the 



string of extraneous characters after 
"COMMAND SEQUENCE IS BEING 
TRANSMITTED TO TANK". 
"A!%1%&Q$25$!5&QTC%F" 
is the string sent to the tank by the 
CHR$(X) function. It ended up on the 
listing (inadvertently) because both 
devices (printer and tank) use the 
same I/O-port address. If you com- 
pare these characters to those in table 
2, you will see that it represents the 



58 February 1981 © BYTE Publications Inc 



Circle 33 on inquiry card. 



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Circle 32 on Inquiry card. 



Circle 34 on inquiry card. 



The 

reachable 

star. 



ne & i /vi puts a quality 300 
bps RS232 modem within reach 
of the smail computer user...the 
same modem selected by IBM, 
GE, RCA, and ADP. "Hie price? 
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STAR models are available 
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commands entered during execution 
of the program. 

The program here, of course, is de- 
signed more as a demonstration than 
as a functional illustration of com- 
puter intelligence. I don't play with 
these interfaces every day, and it is 
easy for me to forget the steps neces- 
sary to enter a program on the key- 



pad. By making it as idiot-proof as 
possible, by prompting the correct re- 
sponse, / can appear more intelligent 
when I demonstrate Big Trak. 

In Conclusion 

Big Trak will not create any earth- 
shaking movement within the robot- 

Text continued on page 64 




Photo 9: A second walkie-talkie is used in the receiving section of the remote-control 
hardware. The working parts of the walkie-talkie have been placed in the same 
enclosure that will shortly house the demodulator circuit. Here again, the speaker has 
been removed from the walkie-talkie and a 10-ohm resistor substituted. 




Photo 10: The originate-type modem demodulator of figure 7 has been constructed on 
a printed-circuit board and placed in this box over the walkie-talkie circuit. The 
modulator section of the circuit board is not used in this application; therefore the in- 
tegrated circuits used only by the modulator have been removed. The circuit board is 
mounted on stand-offs and is powered by two 9 V batteries. A shielded cable and a 
phono jack connect it to the tank-controller interface, mounted inside the Big Trak. 



February 1981 © BYTE Publications Inc 




New power at your fingertips. 



Konan presents Hard Disk 
Control, Tape Control, and 
Serial I/O Boards for S-lOO 
computers. 

Konan, known throughout the industry for its 
leading, innovative, guaranteed controllers 
for S-lOO systems, does it again. Now, it offers 
you more of the expanded capabilities you 
want, 

Take your pick to suit your needs. There's 
the SMC-lOO™ storage module (SMD or CDC 
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coming soon! 



Also, Konan introduces OCTOPORT™ and 
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OCTOPORT™, the 8-port board, offers a real 
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With these and other quality products, 
Konan shows again that when it comes to 
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Call Konan's toll-free order line: 

800-528-4563. 

Or write ta Konan Corporation 
1448 North 27th Avenue 

Phoenix, AZ 85009 
TWX/TELEX 9109511552 

"Alpha Micro AM-500 is a trademark ol Alpha Micro Systems. 

IN CONTROL, SMC-lOO. HARD TAPE. KNX-500, OCTOPORT. and OMNIPORT 
are trademarks ol Konan Corporalion. 




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10-Day Money-Back Policy For Wired & Tested 
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CALL TOLL FREE: 
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From Conneclicut Or For Assistance: 
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Please send the items checked below: 

SWEET SIXTEEN kit; No. S-16 . . . (reg. price 
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'Plus $2 postage & insurance. Connecticut residents 
add sales tax. 
Total Enclosed: S 



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Signature 

Print 

Name 

Address 

City 

Stale 



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I5.NETR0INICS 

RESEARCH & DEVELOPMENT, LTD. 

333 Litchfield Rd., New Milford. CT 06776 



62 February 1981 © BYTE Publications Inc 



Listing 2: An example of the user interaction produced by the program of listing 1. The 
coded command-specification characters transmitted to the tank show up in this print- 
out on the next-to-last line, because the same I/O-port address was used for both the 
remote-control transmitter and the printer interface. 



COMPUTERIZED REMOTE CONTROL 

Command list to be repeated each time (Y or N)? N 
COMMANDS : 

(M)ove (F)ire 

(C)lear (D)ump 

(H)old (G)o 

(R)epeat (D)ump 
(T)est 

Command? M 

(F)orward, (B)ackward, (L) eft, or (R)ight 

? F 

How many feet (1 to 99)? 2 

Command Stored 
Command? H 
Hold how many seconds (total times .lsec)? 20 

Command Stored 
Command? F 
How many shots (1 to 99)? 5 

Command Stored 
Command? M 

(F)orward, (B)ackward, (L)eft,or (R)ight 
? I 
Turn how many degrees (0 to 360)? 90 

Command Stored 
Command? M 

(F)orward, (B)ackward, (L)ef t,or (R)ight 
? F 
How many feet (1 to 99)? 10 

Command Stored 
Command? F 
How many shots (1 to 99)? 6 

Command Stored 
Command? R 
Repeat how many steps? 2 

Command Stored 
Command? G 
COMMAND CONTROL SEQUENCE IS BEING TRANSMITTED TO TANK 



A!%l%SQ$25$!5SQTC%FTRANSMISSION COMPLETE 
Retransmit Same Control Sequence (Y or N) ? 




Photo 11: When the electronic hardware has been built and is fully operational, the Big 
Irak Transport {a cargo trailer) provides a convenient method for dragging the wireless 
communication interface along. 

Circle 36 on Inquiry card. — -#► 



THE SOLUTION STORE 




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FOR FRANCHISE OPPORTUNITY INFORMATION CALL (602) 967-1421 



BANDPASS FILTER AND LI MITER 




9V BATTERY 



=_9V BATTERY 



SERIAL DATA OUT ^ — , 1 /T f 

TO FIGURE 3 < ^— I °l I 



Number 


Type 


+ 9V 


-9V 


GND 


IC1 


LM741 


7 


4 




IC2 


LM1458 


8 


4 




1C3 


XR2211 


1 




4 


IC4 


CD4011 


14 




7 



Figure 7: The demodulator section of an originate-type modem. This is required at the receiving end of the computer/Big Trak link to 
decode the 2025 Hz and 2225 Hz tones received by the walkie-talkie. See photos 9 and 10 for views of the receiving system. 

The XR2211 phase-locked loop is produced by Exar Integrated Systems, POB 62229, Sunnyvale CA 94086. Capacitors marked 
with an asterisk (*) should be the type made from Mylar. 



Text continued from page 60: 

ics community, but neither will it go 
unnoticed by those of us who like to 
play with toys. I hope you will 
recognize the independent capability 
of the wireless serial-communication 
link and use it in another application. 
As regards extensions of the con- 
trol concept, a few more ideas came 
to mind while I was writing. The 
wireless communication method de- 
scribed in this interface is a one-way 
link, computer to remote peripheral 
device. However, the modem boards 
used in the prototype have full- 
duplex capability, even though only 



half of each unit is used. Further- 
more, within the tank-controller in- 
terface, I did not use the transmit por- 
tion of the UART. 

If two more walkie-talkies oper- 
ating on a different frequency are 
added, or if the two existing units 
are switched back and forth between 
send and receive, we could conceiv- 
ably receive data sent back from the 
tank. The required interface com- 
ponents are presently available in the 
hardware (the other halves of the two 
full-duplex modem boards) but are 
not utilized. 

What data might the tank send 



back7 Do you remember that article I 
did a while back on the Polaroid 
Ultrasonic Ranging System? [In case 
you don't, see "Home In on the 
Range! An Ultrasonic Ranging Sys- 
tem," BYTE, November 1980, page 
32. ...RSS] 

I'm sure you get the picture, but 
unfortunately I didn't have enough 
time to add that feature now. How- 
ever, if you don't mind looking at Big 
Trak once more at a future time, I'd 
like to consider adding "eyes" and 
demonstrating control programs that 
exhibit more machine intelligence. 



64 February 1981 © BYTE Publications Inc 



Circle 37 on Inquiry card. 



First compare quality. 
Then compare cost. 

Morrow Designs' 10 megabyte 
hard disk system: $3,695. 



MORE MEMORY. LESS MONEY. 

Compare Morrow Designs' DISCUS 
M26™ hard disk systems 
to any system available 
forS-100 or Cromemco 
machines. First, compare 
features. Then, com- 
pare cost per mega- 
byte. The M26 works 
out to under $200 a 
megabyte. And the M 10 is 
about half the cost of com- 
peting systems. 

COMPLETE SUBSYSTEMS 

Both the M10 (8"), and the M26 
(14"), are delivered complete with 
disk controller, cables, fan, power sup 
ply, cabinet and CP/M® operating 
system. It's your choice: 10 Mb 8" 
at $3,695 or26 Mb 14"at $4,995. 
That's single unit. Quantity prices are 
available. 

BUILD TO FOUR DRIVES. 

104 Megabytes with the M26. 40+ 
megabytes with the M10. Formatted. 
Additional drives: M26: $4,495. 
M10: $3,195. Quantity discounts 
available. 

S-100, CROMEMCO 
AND NORTH STAR? 

The M26 and M10 are sealed-media 
hard disk drives. Both S-100 controllers 
incorporate intelligence to super- 
vise all data transfers through four I/O 
ports (command, 2 status and data). 
Transfers between drives and control- 
lers are transparent to the CPU. The 
controller can also generate interrupts 
at the completion of each command 
...materially increasing system through- 
put. Sectors are individually 
write-protectable for multi- 
use environments. North 
Star or Cromemco? 
Call Micro Mike's, 
Amarillo, TX, 
(806)372-3633 
for the software ♦ " 

package that allows 
the M26and M10to run 
on North Star DOS. MICAH of 




Morrow Designs' 
26 megabyte 
hard disk system: 
$4,995. 




Sausalito, CA, (415) 332-4443, 
offers a CP/M expanded to full 
Cromemco CDOS compatibility. 

AND NOW, MULT-I/O.™ 

Mult-I/Oisan I/O controller that allows 
multi-terminal and multi-purpose 
use of S-1 00 and Cromemco computers. 
Three serial and two parallel output 
ports. Real time clock. Fully program- 
mable interrupt controller. Designed 
with daisy-wheel printers in mind. 
Price: $299 (kit), $349 assembled 
and tested. 

MAKE HARD COMPARISONS. 

You'll find that Morrow Designs' hard 
disk systems offer the best price/ 
performance ratios available for S-100, 
Cromemco and North Star compu- 
ters. See the M26 and M10 hard disk 
subsystems at your computer dealer. 
Or, write Morrow Designs. Need infor- 
mation fast? Call us at (415) 524-2101 . 

Look to Morrow 
for answers. 



MORROW OESIGN5 



"CP/M is a trademark of Digital Research Corp. 
•Cromemco is a trademark of Cromemco. Inc. 
North Star is a trademark of North Star Computers, Inc. 



5221 Central Avenue 
Richmond. CA 94804 



n 



Readers who wish to experiment with the wireless interface or want to 
build an inexpensive modem may order the following: 

Blank printed-circuit board (shown in photos 7 and 10) and construction 
manual; can be built as either answer or originate full-duplex modem. 
Full details of the circuit on the board are described in "A Build-It- 
Yourself Modem for Under $50, " BYTE, August 1980, page 22, and con- 
struction manuals included in each board. 



Single circuit board 
Two or more boards 



$14 
$12.50 each 



Complete kit (printed-circuit board, components, and manual) necessary to 
build a full-duplex originate modem. 



Complete kit 



$39.95 



Order these from: 



The MicroMint Inc 
917 Midway 
Woodmere NY 11598 
(516) 374-6793 

Please add $2 for shipping and handling. New York residents please add 
7% sales tax. 



MARK GORDON 

COMPUTERS 

DIVISION OF MARK GORDON ASSOCIATES. INC. 

P.O. Box7 7,Charlestown, MA 02129 (617)4917505 



COMPUTERS 

Atari 800 W I 6I( 799.00 

Level-ll I6K Sysiem 659.00 

Model II G4K SyMem 3499.00 

I 61< Model III 859.00 

DISK DRIVES 
40 Track 5' • Inch drive 314.00 

80 Track 5 'A 544.00 

4 Disl. Drive Cable 39.00 

PRINTERS 

Centronics 730 599.00 

EpsonMX80B .499.00 

Centronics 737 849.00 

OUidata Microline 83 1044.00 

Integral Data 440C 999.00 

NEC 5510 w tractor . . 2679.00 

Oltidata Microline 80 599.00 

Diablo 630 2495.00 

MISC HARDWARE 

Expansion int TRS 80IOIt) 249.00 

Novation Cat modem 159.00 

I OK Memory Kit 4 1.99 

Leedex Monitor 109.00 

Printer Cable for above 49.00 

ISO-2 Isolator 54.00 

AC LINE FILTER 24.00 

STORAGE MEDIA 

Verbatim box 10-5' j 25.00 

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Editor's Note: Steve often refers to 
previous Circuit Cellar articles as 
reference material for the articles he 
presents each month. These articles are 
available in reprint books from BYTE 
Books, 70 Main St, Peterborough NH 
03458. Ciarcia's Circuit Cellar covers ar- 
ticles appeating in BYTE from September 
1977 thru November 1978. Ciarcia's Cir- 
cuit Cellar, Volume II presents articles 
from December 1978 thru June 1980. 



BYTE's Bits 



Johns Hopkins 
Contest on 
Applications for the 
Handicapped 

Johns Hopkins University is sponsor- 
ing the First National Search for 
Applications of Personal Computing to 
Aid the Handicapped. The contest is be- 
ing funded jointly by the National 
Science Foundation and Radio Shack. 

The contest addresses the full spec- 
trum of physical and mental handicaps, 
including: learning disabilities, visual 
handicaps, hearing, language, neuro- 
muscular or neurological disorders, and 
limitations of movement. There are three 
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dent, amateur, and professional — with 
both cash and equipment prizes awarded 
in each category. Contestants must be 
residents of the United States. Categories 
of submission include: prototypes, com- 
puter programs, and system concepts/ 
ideas. Individual rights remain with the 
contestant. 

We applaud all parties concerned for 
conducting this worthy effort. 

The deadline for submissions is June 
30, 1981. For a descriptive flyer and 
further information, write to: 

Personal Computing to Aid the 

Handicapped 

Johns Hopkins University 

POB 670 

Laurel MD 20810B 



66 February 1961 © BYTE Publications Inc 



Circle 38 on inquiry card. 



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WINS 

The Ohio Scientific Software Game 



Selecting software for your Ohio 
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A Beginner's 
Guide to Spectral Analysis 

Part 1: Tiny Timesharing Music 



Mark Zimmermann 

9410 Woodland Dr 

Silver Spring MD 20910 



We live in two worlds that co-exist 
in space and time; they touch each 
other and interpenetrate at every 
point and at every moment. In fact, 
each world contains the other within 
it. 

One is a world of forms, of colors, 
of sounds; the other is a world of 
complex numbers, of mathematical 
functions. Most people aren't aware 
of this second world, but that doesn't 
make it any less valid as an expres- 
sion of reality. It's not hard to peek 
into this "alternate universe": this ar- 
ticle and the accompanying programs 
will attempt to aid you in doing so. If 
a student devotes some time to the 
concepts suggested here, he'll find 
himself rewarded with a set of extra- 
ordinarily useful tools. Some facts 
which aren't obvious in one world are 
obvious in the other; some tasks 
which are slow, laborious, and ex- 
pensive in the first world become 
quick and cheap in the second. 

My description may sound a bit 
like Oriental mysticism, but it's not! 
This article will try to sketch an in- 
troduction to Fourier analysis, one of 
the most powerful developments in 
modern mathematics. It will empha- 
size the feel of the subject, not the 
complicated algebraic formalisms. 
No advanced mathematical training 
is required, but it may help to have 
access to a small computer for some 
parts of the discussion. The programs 
that I've written for illustrative pur- 
poses are in either BASIC or 6502 
assembly language, and were specifi- 
cally designed for the 8 K-byte Com- 
modore PET. It should be a fairly 
straightforward process to adapt 
these programs to comparable ma- 
chines. 



The first part of this article will in- 
troduce the one-dimensional Fourier 
transform, and emphasize its impor- 
tance to music and human perception 
of sound. Included is a "tiny time- 
sharing" program that is both edu- 
cational and enjoyable. It generates 
simple musical themes using the 
building blocks of intervals, and 
varies these themes via a series of in- 
versions. New musical elements are 
introduced pseudo-randomly, so the 
patterns never repeat, and the tone 
quality is also constantly varied. All 
of this uses only about 0.1% (yes, 



The "tiny timesharing" 

program generates 

simple musical themes 

using only 0.1 %of the 

computer's time. 

one-tenth of one percent!) of the com- 
puter's time, which allows other pro- 
grams to be run simultaneously with 
no noticeable loss of speed. 

In the second part of this article, I 
will outline the simple extension of a 
one-dimensional problem into a two- 
dimensional plane. The program that 
illustrates this process uses pictures 
drawn on the PET's video-display 
screen and transforms them by a pro- 
cess similar to that of making a holo- 
gram with coherent light. 

The references at the end of each 
part should be useful for anyone who 
wants more information on the topics 
encountered. You may also find it 
helpful to consult your neighborhood 
Fourier guru, who has probably 
chosen to be reincarnated as an elec- 



trical engineer or radio astronomer. 

The Frequency Domain 

The central idea of Fourier (or spec- 
tral) analysis is quite simple. One of 
the best ways to understand it is to 
think about a musical chord, pro- 
duced by simultaneously hitting sev- 
eral keys on a piano. Suppose you 
play a chord and want to record it — 
how can you do that7 

One way to preserve a chord for 
posterity would be to record it on a 
tape deck or (if you collect antiques) 
on a gramophone wax cylinder. In 
either case, the method of recording is 
essentially the same: the sound im- 
pulses are translated into magnetic 
field patterns, or into the wiggles of a 
groove, and stored just as your ear/ 
microphone perceives them. If you 
had an oscilloscope, you could dis- 
play the sound on a screen and photo- 
graph it. 

But there's also a completely dif- 
ferent way to save the chord. You can 
draw a musical scale and write down 
the notes that are hit. This scale 
doesn't show the moment-by-mo- 
ment variations of air pressure 
against your eardrums; instead, it 
relates something about the frequen- 
cy of these pressure waves, and the 
set of frequencies that is being created 
by the vibrating piano strings. 

A recording method that stores a 
sound as a function of time is said to 
work in the time domain. A method 
that breaks a sound up into its con- 
stituent frequencies and records the 
amount of each frequency component 
that went into the original sound is 
said to work in the frequency do- 
main. 

The usual musical notation for 



68 February 1981 © BYTE Publications Inc 



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notes on a scale doesn't give enough 
information to completely recon- 
struct the original chord. Even if each 
piano key produces a pure tone with 
no harmonics or distortions, you 
should still specify more than which 
keys were punched. You must say 
precisely how loud each note in the 
chord was played and the precise time 
that each note began (ie: the ampli- 
tude and the phase of each pure note 
in the chord). Given that amount of 
data, the original sound can be repro- 
duced exactly. The frequency-domain 
method of recording then contains as 
much information as the conven- 
tional time-domain recording techni- 
que. 

That's really all there is to Fourier 
analysis. There are, of course, precise 
mathematical formulas for transla- 
tion from the time to the frequency 
domain, and back. There are also 
modern improvements on these for- 
mulas, such as the fast Fourier 
transform, which can do the same job 
in much less time than the old-fash- 
ioned method. But the basic ideas re- 
main the same: the Fourier transform 
is a technique for changing notation 
from one way to another in order to 



record the same information. 

There are many references (see re- 
ferences at the end of this article) 
that explain the mathematics of the 
Fourier transform. I'd like to avoid 
these, and try instead to explain the 
meaning of the transform, and the 
uses to which it can be put. 

Why Transform? 

I have already mentioned the ap- 
plication of Fourier analysis to music, 
and I'll return to this topic later. 
There are numerous other uses for the 
transform concept. Almost any 
wave-like phenomenon can show in- 
teresting behavior when looked at in 
the frequency domain. Light, when 
spread into a spectrum, reveals infor- 
mation about the source that pro- 
duced it: that's how astronomers 
determine the composition of distant 
stars. (The word "spectrum" is the 
source of the term "spectral 
analysis.") Radio signals, grouped at 
different frequencies, carry hundreds 
or thousands of simultaneous tele- 
phone calls, TV broadcasts, etc. A 
receiver simply performs a partial 
Fourier analysis in order to separate 
one- program from the crowd. Ocean 



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waves can be resolved into frequency 
components, each traveling with its 
own speed. This approach helps, for 
example, in understanding how tsu- 
namis (tidal waves) are created by 
undersea earthquakes and travel 
thousands of miles across the water 
before cresting on a shore. 

Fourier analysis is also applicable 
to things that aren't functions of time. 
In calculating the heat distribution 
within a nuclear reactor core, one 
useful method involves breaking up 
the spatial dependence of the tem- 
perature into pieces that vary with 
different spatial frequencies. Similar 
techniques work to explain the shape 
of a soap film over a bent wire loop, 
the electrical field patterns inside a 
microwave cavity resonator, or the 
air density and pressure variations in- 
side an organ pipe. (In the latter two 
cases, time dependences also exist as a 
part of the problem; the time depen- 
dences can be easily solved once the 
spatial Fourier analysis problem is 
understood.) 

In recent years, myriad practical 
applications of spectral analysis have 
been developed, particularly in elec- 
trical engineering. If a signal is first 
transformed into the frequency do- 
main, it often becomes easy to filter 
out noise and interference. On the 
other hand, by scrambling frequency 
components you can make a voice 
incomprehensible (unless the 
scrambling pattern is known) and 
allow relatively secure com- 
munications over a channel that is 
not secure. Quite often, it's most effi- 
cient to manipulate a signal by trans- 
forming it into the frequency domain, 
working it over, and then trans- 
forming back; the cost of trans- 
forming is more than repaid by the 
speed and convenience of many oper- 
ations when applied to the frequency 
components of a function. 

In the field of computing, Fourier 
analysis concepts have proved to be 
extremely helpful. The invention of 
faster algorithms as an aid in multi- 
plying large numbers got its start 
from fast Fourier transform theo- 
rems. The spectral test for random 
number generators, one of the most 
powerful tests known for detecting 
non-random biases, is a Fourier 
technique. Even before electronic 
computers existed, mechanical "cal- 
culating engines" were built to do 
Fourier analysis because of the impor- 
tance of the subject. 



70 February 1981 © BYT1 Publications Inc 



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Omni Printers 
bom Texas 
Instruments 

The 810 - Lfat S1895. SALE! S1795. 
The 820 (Ro) Package — 
Includes machine-mounted 
paper tray and cable. A com- 
pressed print option and device 
forms control are standard fea- 
tures. $2,155. 

The 820 (KSR) Package - 
Includes lull ASCII Keyboard plus 
all of the features on the RO 
S2395. 




APPLE 

We carry the most complete 
inventory of Apple computers, 
peripherals, and software. CALL! 
Can Best Selling Apple System. 
Save over S250 on our most pop- 
ular Apple System. System 
includes a 48K Apple U. Apple 
Disk. D053.3, 8< Controller, and a 
Sup R. Mod RF Modulator, 
list: S2070. 

CompuMait Sale Price: $1795. 



COMMODORE 

CompuMart has delivered more 
Commodore computers in the 
US. than any other dealer. Call 
us now for low prices and spe- 
cial deals. 
NEW FOR PET, 
Visicalc (Need 32K 8c a disk 
drive) $199. 
Word Pro L 
$29.95 - Word 
Pro 2, $99.95 
- Word Pro 3, 
$199.95 - 
Word Pro 4, 
$299.95. 




NEW bom Apple foi the Apple 
11 

Dos 3.3 Convert disks to 16 sector 
format lor 23% more storage and 
faster access $60. 

SOFTWARE FROM APPLE 
Apple Plot. The perfect graphic 
complement for Visicalc. $70 
Dow Jones News 8c Quoles $95 
Adventure (Uses 48K) $35 

DOS Tool Kit $75 

Apple Fortran $200 

Tax Planner $120 

FROM PERSONAL soltware 
Visicalc $149 

Desk Top Plan $99 

NEW FROM MUSE 
The Voice $39.95 

Super Text $99.00 

Address Book $49.95 

Miscellaneous Apple II 
AccessoiieS: 

Easy Writer (80 coL need a 
Videx) $249 

Easy Mover $49 

Easy Mailer $69 

HARDWARE ACCESSORIES FOR 
APPLE 

Silentype Printer w/x face $595. 
Super Sound Generator (mono) 
$159 (stereo) $259 

light Pen $249 

X-IO Controller (plugs into pad- 
dle port) $49 



Dysan Diskettes — Single side. 

Single density, Hard or Soft Sector 

$5. ea. 

Memoiex 3401's — 5 1 A discs 

$3.25 with hub ring for Apple 

$3.50. 

Memoiy IntegratedCircuits — 

Call lor qty. discounts when 
ordering over SO units. 
Motorola 4116 (200 Nanosecond 
Plastic) $4.50 ea. 
Faiichild 2114(Standard Power. 
Plastic) $4.50 ea. 



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plete line of MATROX PRODUCTS. 

Call lor specs. 

COMPUMART now offers the 
ENTIRE DEC LSI-11 PRODUCT LINE 
Call lor prices 8c delivery. 

NOVATION CAT to 
ACOUSTIC MODEM 

Answer Originate, 300 Baud Bell 

108. Low Profile Desiga $179.00 

NEW! D-CAT 

Direct Coupler from Novation 

$199. 



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We want to clean out our inven- 
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this we've priced our Exidy 
equipment so low you'll have to 
call us for prices. 

New liom VIDEX! — Video Term. 
SO Col. x 24 line, 7x9 Matrix plug 
in compatible board for the 
Apple n. Price $325 without 
graphics EPROM With graphics 
EPROM $350. 

S.S.M. Serial 8c Parallel Apple 
Interface $225 

ABTs Numeric Key Plan $110 
California Microcomputer 
Keyboard ..a^ass^ $195 



Mountain Computei — Expan- 
sion accessories for your Apple 
Introl - lO System $289 

Super Talker $299 

The Music System $545 

ROM plus board w/Keyboard 
filter $199 

Clock Calendar $280 

16 Channel A to D Converter 
$350 

Apple Expansion Chassis $650 
ROM Writer $175 



NEW bom Lear Sieglei! 

We have the following Lear 
Siegler Terminals in stock at 
prices too low to print — Call lor 
quotes. 

ADM — 3A Indus- 
tries favorite 
dumb terminal 
lor some very 
smart reasons. 
ADM — 3A + 
NEW from Lear 
Siegler. CALL! 
IT S HERE! - It 
is the new 
Intermediate Terminal 
from Lear Siegler. Call for details. 




Limited Time Ober, Oux Hazel- 
tine prices slashed again! 

Haezltine 1410 

List 3850 Compumart $749 
Hazeltine 1420 
List $995 CompuMart $825 
Hazeltine 15CO 
List $1095 CompuMart $965 
Hazeltine 1510 

List $1395 CompuMart $1135 
Hazeltine 1520 
List $1585 CompuMart $1199 
Hazeltine 1552 
list $1395 CompuMart $1235 




Compum art's exclusive ATARI 
SPECIALS 

ATARI 8CO Personal Computer 
System — Comes with 8CO oper- 
ators Manual. 16K Rany Mem- 
ory module, IOk ROM 
Operating System, 
Power Supply, TV 
Switch Box $950. 



EXCLUSIVE bom CompuMart! 
Special Ofier. Zenith Coloi 
Video Monitor tor $379! 

NEW FROM SANYO - Four Great 
Monitors at Low CompuMart 
Prices. Sanyo's new line of CRT 
data display monitors are 
designed for the display of 
alphanumeric or graphic data. 

9 " Sanyo Monitor $169. 

12 " Sanyo Monitor $289. 

12 " Sanyo Monitor with green 

screen $299. 

13" Sanyo Color Display Monitor 

$495. 



SEND FOR OUR 
FREE CATALOG 




< 



HP-41C Calculator $288.00 

Memory Modules: For storing 
programs or up to 2,000 linesof 
program memory . $45.00 ,-'-;- . 
"Extra Smart" Card 
Reader. Records pro- 
grams and data back 
onto blank mag- 
cards . $199.' 
The 
Printer. 
Upper and 
Lower case, 
High resolution 
plotting, Portable Thermal 

operation $355.00 

Application Modules ... $45.00 




NEWI The PMC-80, The new 

computer that's software com- 
patible with the TRS-8Q Level 11 
16K at $645. 

ACCESSORIES FOR PMC - 80 
EXP-lOO S-lOO Bus Expander 
Disk. Printer, RS232 I/O $410. 

S-32K S-lOO Bus 32K RAM Board 
for EXP-lOO $295. 

CAB-40 Cable 12 " long ribbon 

cable 

lor EXP-lOO. -- t $25. 




PERIPHERALS 

Atari 410 Program Recorder 
(FREE w/purchase of Atari 
8CO) $89.95 

Atari 810 Disk Drive 
($100 off with purchase) 

$699.95 
NEW Dual Disk double density 

$1499.95 
825 Printer (Centronics 737) 

$995.00 
RS232 Interface w/Cable 
$249.95 
NEW! light Pens $74.95 
NEWI Visicale for Atari ATARI' 

$199.00 



A 



IMPORTANT ORDERING INFORMATION All orders must include 4% 
shipping and handlin g. Mass. residents add 5% sales tax. Michigan 
residents 4% lor sales tax. Phones open irom 8;30 a.m. to 7:00 p.m.. 
Mon-Fri: 1 1:00 a.m. to 4:00 p.m. Sat. RO.'s accepted lrom Dun & 
Bradstreet rated companies-shipment contingent upon receipt of 



signed purchase order. Sale prices valid lor month ol magazine 
date only-all prices subject to change without notice. Our Ann 
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to 5:00 p.m. Saturdays. Stop by and visit. 




CompuMart's Microllex 65 Sys- 
tem lor your AIM Includes: 
Adapter Buffer Module w/4-slot 
module stack. 8K RAM module, 
16K PROM/ROM module, Asyn- 
chronous communications Inter- 
face, and Power Supply $1,29 
Call 01 writer for our complete 
Microllex 65 brochure 



HP-S5 

Hewlett-Packard's Personal Com- 
puter lor Industry, This extremely 
portable computer features 
extended BASIC to solve your 
problems quickly and efficiently 
along with an advanced 
graphics system to enhance 
communication. 
HP-S5 ACCESSORIES 
We carry H.P. Peripherals (Disk 
Drives to Graphics Plotters) 
Enhancements (BASIC Training, 
General Statistics, Financial Deci- 
sion Math. Linear Programming 
$95 ea).- HP-85 Accessories. 
(Enhancement ROMs, ROM 



ROCKWELL AIM 65 

Our AIM system includes 4K AIM 
with BASIC interpreter assembler. 
Power Supply, Cassette recorder 
& Enclosure $79 . 

4K ATM -65 $499. 

PL65 High Level Language $125. 
Paper lor the AIM (roll) $2.50 

Rockwell's 4-slot 
Motherboard (sale) $175. 



drawer. Overhead Transparency 
Kit), Supplies (Plotter Pens, Tape 
Cartridges),- Interface Modules 
(HP-IB Interface, HP-IB Intercon- 
nect Cables, Serial (RS-232C) 
Interface Module). 
We can get your every HP 
peripheral made for the HP-85. 
CALL FOR COMPLETE DETAILS 8c 
SPECS. 

The 
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Quality, Versatility, 
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CompuMart has been serving the 
computer needs of industry since 1971. 

We stock, for immediate shipment, only 
those products from the finest micro-computer 
manufacturers. 

And any product, except software, can 
be returned within lO days for a full refund — 
even if you just change your mind. 

We also honor all manufacturers' 
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ufacturer's local service center. 



Call us for more information on products, 
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We have a staff of highly knowledgeable 
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SYSTEMS 




iCOMPUMART 



65 BENT STREET, DEPT. 000, RQ BOX 568 
CAMBRIDGE, MA 02139 



Circle 42 on inquiry card. 



Listing 1: RMS Spectrum Plot for the Commodore PET. This program calculates and 
displays on the screen the Fourier components produced by a given bit pattern in the 
PET's shift register. The data is "played" with some extra hardware, as detailed in figure 
1. 

1 REM N-BIT POWER SPECTRUM ANALYZER, COPYRIGHT 1979 MARK ZIMMERMANN 

10 INPUT "NUMBER OF BITS"; NB: INPUT "HIGHEST HARMONIC"; HH 

30 NM = NB - 1 : DIM S(NM), C(NM), F(NM), TS(NM,NM), TC(NM.NM) 

40 FOR I = 0TONM: X = 2*t*I/NB: S(I) = SIN(X)/ir: C(I) = COS(X)/?r: NEXT I 

50 INPUT "NOTE (1 TO 255)"; NT: POKE 59467,16: POKE 59464,NT 

60 FOR 1 = TO NM: FOR J = TO NM: X = I*J: Y = X+I: X = X-NB*INT(X/NB): 

Y = Y-NB*INT(Y/NB) 

70 TS(I,J) = S(Y) - S(X): TC(I,J) = C(X) - C(Y): NEXT J: NEXT I 

80 REM SET UP MATRICES TO ALLOW SPEEDY INTEGRATIONS LATER 

100 INPUT "TONE QUALITY"; D: IF D<256 THEN POKE 59466,D 

1 10 DD = D: REM MAKE BINARY REPRESENTATION OF D IN LINE 120 

120 FOR I = NM TO STEP - 1: F(I) = DD-2*INT(DD/2): DD = INT(DD/2): NEXT I 

130 PRINT "[cls]";D;" = ";: FOR 1 = TO NM: PRINT F(I);: NEXT I: PRINT 

150 FORK = l TOHH: X = K-NB*INT(K/NB): C=0:S = 

160 FOR J = TO NM: C = C + TS(X,J)*F(J): S = S + TC(X,J)*F(J): NEXT J 

170 C=C/K: S = S/K: A = SQR(C*C + S*S) 

180 PRINT "[home]"; : FOR I = 1 TO STEP - 0.05: IF A > I THEN PRINT TAB(3*K); " ♦ "; 

190 PRINT: NEXT I 

200 NEXT K: FOR 1 = 1 TO HH: PRINT TAB(3*I- 1);I;: IF I> 8 THEN PRINT "[cl]"; 

210 NEXT I: PRINT 

220 GOTO 100 



100K 



GND | — s. 

(PIN N ) I ? ~ 



15/iF 

-H( — o 



.0.01/tF 



TO AMPLIFIER 



-o 



m 




SPEAKER 



2.2 K 
CB2 [ ^> VIAr- 




2N2222 



Figure 1: Circuits to adapt the PET to a common audio amplifier (top), or to produce 
an audio output directly (bottom). 



Music and the Fourier Transform 

Unlike the other senses, the ear 
seems to work naturally in the fre- 
quency domain. Physiologically this 
may result from the structure of the 
cochlea in the inner ear; sounds of 
different frequencies stimulate dif- 
ferent spatially separated areas (so 
that the motion of the eardrum is 
Fourier transformed!). It is both in- 
teresting and educational to experi- 
ment with sounds of various frequen- 
cy spectra. A microcomputer can be a 
great aid to this kind of experimenta- 
tion, since it can reliably generate 



precise, easily modified waveforms, 
as well as perform the mathematical 
work required to calculate the spec- 
trum of any particular wave. Both the 
pitch and the tone quality are vari- 
able. 

The program RMS Spectrum Plot 
(see listing 1) was designed for just 
this kind of experiment. The mathe- 
matical parts can be run on any com- 
puter that understands BASIC; on the 
PET, the spectrum is graphically plot- 
ted on the video display, but a nu- 
merical output would be an accept- 
able alternative. This program also 



makes use of the recirculating shift- 
register in the MOS Technology 6522 
VIA (Versatile Interface Adapter) in- 
tegrated circuit in the PET. The VIA 
has an output to pin CB2 of the PET's 
port edge connector. Any trivial am- 
plification circuit (see figure 1) can be 
used to amplify and isolate this out- 
put to give an audible tone. Many 
other microcomputers have similar 
tone-generation capabilities; other- 
wise, a separate waveform generator 
may be used to study the sounds that 
are being Fourier analyzed. 

RMS Spectrum Plot performs a 
straightforward N-bit power-spec- 
trum analysis. For use on the PET and 
most other microcomputers N = 8 is 
the case of interest, but there is no 
harm in making a more general pro- 
gram and allowing for an arbitrary 
N. (Note that for N not equal to 8, the 
tones produced by the PET's shift 
register are not the same as the tones 
being analyzed by the program. Also 
note that for N greater than 16, PET 
BASIC w ill not correctly handle the 
array look-up operations for arrays 
TS and TC, which would need to 
have more than 256 elements.) I 
won't go into the mathematical oper- 
ations that are being performed in the 
course of the spectral analysis: some 
of the references cited later do that in 
great detail. Instead, 111 try to explain 
the results, the physics and the physi- 
ology that the program helps explore. 

Earlier I mentioned that in order to 
describe a sound completely in the 
frequency domain, you must provide 
more than just the list of frequencies 
that went into the original sound. A 
complete specification also requires 
the amplitude of each frequency com- 
ponent and its phase. By phase, I 
mean a measure of where a sinusoidal 
signal is in its cycle of 0° to 360° at 
some moment of time. (For example, 
the functions sin(f) and cos(f) look 
very similar, but one is 90° out-of- 
phase with the other.) Two sounds 
with the same set of component fre- 
quencies and the same amplitude can 
look completely different when dis- 
played on an oscilloscope, and they 
make completely different wiggles in 
a phonograph groove (see figure 2). 

So, phase information is crucial for 
the accurate reconstruction of the 
original sound. High-fidelity am- 
plifier and speaker advertising em- 
phasize this — you must spend lav- 
ishly in order to get really good, 
precise sound reproduction. Or must 



74 February 1981 © BYTE Publications Inc 



Circle 43 on Inquiry card. 



For those special people who've 
stepped ahead with a mini-computer 







maxej 



Mini-FW 



■BBAmnhShB 



maxell 

Mini-Floppy Disk 





Maxell offers a way to stay ahead. 



A Maxell 5Va" Mini-Disk will consistently let you maxi- 
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involvement with it grows, tomorrow as well. Maxell 
Mini-Disks are ail made with the same exacting 100% 
certification and critical dependability of the Maxell 8" 
Floppy Disk. So you know your 5Va" Maxell Mini-Disks 
meet or exceed the same ISO and Shugart specifica- 
tions industry requires. 



There are double density Maxell single and double- 
sided 5 1 /4" Mini-Disks for soft and hard sector systems. 
And 8" Maxell Floppy Disks for every disk drive config- 
uration. See your computer supply dealer or write to us 
for more information. If you are a computer products 
dealer, write for the growing opportunities Maxell 
Business Products Division offers you with our 8" Floppy 
and 5Va" Mini-Disks. 



maxell 




BUSINESS PRODUCTS DIVISION 

Maxell Corporation of America, Business Products Division, 60 Oxford Drive, Moonachie, N.J. 07074 Tel: 201-440-8020 



1111 

f(t) = sin(t) + — sin(3t) + — sin(5t) + — sin(7t) + — sin(9t) 
3 5 7 9 




1111 

f(t) = sin(t) + — sin(3t) sin(5t) + — C0S(7t) sin(9t) 

3 5 7 9 

Figure 2: Different sounds that are composed of the same frequencies. These wave- 
shapes are made up of the same component frequencies, but with a variation in phase 
between them. 



you7 The program in listing 1 allows 
you to see the difference that phase 
information makes in perceived tone 
quality. In my experiments, I've 
found it to make no difference what- 
soever. This agrees with most of the 
unbiased technical references I've 
read on the subject. The human ear is 
a marvelous Fourier analyzer as far as 
separating sounds into their compo- 
nent frequencies, but the ear seems to 
throw away almost all data about the 
phase of the sounds. (Perhaps some 
phase information helps to determine 
whether sounds are coming from the 
left, right, or in front of a listener, but 
that too is unclear.) 

Even without phase information, 
sounds of the same fundamental fre- 
quency produced by RMS Spectrum 
Plot can reveal an interesting variety 
of textures as their bit patterns are 
changed. The program allows the 
user to set the shift register shift rate 
by choosing the value of the variable 
NT, between 1 and 255. The fun- 
damental frequency of the output is 
then determined by the simple for- 
mula: 



frequency = (62,500 Hz)/(NT +2) 

For example, NT = 140 closely ap- 
proximates the standard frequency of 
440 Hz, the note A above middle C. 

Once the frequency of the note is 
chosen, RMS Spectrum Plot allows 
you to hear what an arbitrary bit pat- 
tern (waveform) sounds like, while 
the machine does a spectral analysis 
of the pattern and displays the 
results. These notes are composed of 
a fundamental frequency component, 
called /, plus varying amounts of 
sound energy at frequencies 2f, 3f, 
4f,... — the harmonics of the fun- 
damental tone. After line 170 is ex- 
ecuted, for each frequency KXf, the 
variables C and S contain the amount 
of the Kth harmonic of the signal 
which looks like a cosine (in C) or like 
a sine (in S). A = SQR(C XC + SxS) 
is the amplitude of the Kth harmonic 
(the thing that the ear is sensitive to); 
it is this amplitude A which is plotted 
on the screen (see photos la, lb and 
lc for examples). 

The best thing to do now is to stop 
reading and to experiment a bit with 






<APPLE WORLD 

3-D ANIMATED COLOR GRAPHICS 
Written in machine code. 
The program made famous on national T.V.I 
by Paul Lutus 



APPLE WORLD turns your Apple into a sophisticated 
graphics system capable of creating animated 
three-dimensional color images, protecting them in 
true perspective on the screen, rotate them, move 
them closer, furtheraway, and many other exciting and 
imaginative things. 

Draws objects with 65,000 points per side. 

A powerful screen-oriented text editor is included to 
facilitate image fomation. This program was recently 
featured on Tom Snyder's Prtme Time Saturday TV 
Show and is now available for sale. 

APPLE WORLD'S powerful editor is so easy to use that 
children wilt love it. Youcan now "sketctV'your dream 
house, boat, car, or fantasy empire. Then view it as it 
would be seen from 10.000 feet, or you can ZOOM in 
until the screen is filled with a doorknob. You could 
then go inside and move from room to room 
examining furniture placement as your screen rotates 
within the room. Images or specific parts of images 
can easily be saved to disk or printer. 

Does all this sound like science fiction? 

You wontthinksoafteryou have visited Apple World. 

INTRODUCTORY PRICE $59.95 

36 page manual included 

For 48K Apple II or Plus with Disk 



3-D 









SUPERGRAPHICS 

& 3-D GAME DEVELOPMENT SYSTEM IN COLOR 
' ny Paul Lutus 

Watch colorful butterflys. birds, fly across your Apple 
or Atari screen with true3dimensional perspective. 
Have rocket ships fly out at you in this incredible high 
speed graphics package. 3-D SUPERGRAPHICS" is 
a 6502 machine language program that will 
interface to your Basic or machine language 
programs or games using simple ■'DOS-like" commands. 

Fealuras include: 

• Simple image entry through editor 

• Objects up to 256 points per side 

• Uses all hi-res colors 

• Allows mixed colored text & graphics 
for promots and captions 

• Translates on 3 axes 

• Individual axis scales 

• 21 different commands 

• Rotate object 1.4° to 360° 
increments at machine speeds 

FOR 48K APPLE II OR PLUS WITH 
DISK II $39.95 FOR DISK 

FOR ATARI 800 WITH 40K MEMORY 
(DISK OPTIONAL) 

' $39.95 FOR TAPE 



OTHER SOFTWARE 

APPLE COMPUTERS 

Super Space Wars S 9.95 

States & Capitals 9.95 

Moving Point 

Average 19.95 

Stock Options 24.95 

Finance 12.95 

Bonds 12.95 

COMMODORE PET 

Slock Options 24.95 

Finance 12.95 

Bonds 12.95 

Stock Analyzer 22.95 

Mortgage 14.95 

Space Intruders ("Best 

Game of 1979").. 19.95 

Jury/Hostage 9.95 

Kentucky Derby/ 

Roulette 9.95 

Alien I.G./Tank 9.95 

Tunnelvision/Maze 

Chase 14.95 

Submarine Attack 9.95 

Battle of Midway 7.95 

Laser Tank Battle 9.95 

Swarm 14.95 

Baseball 9.95 

Super Startrek 14.95 

PET Music Box 29.95 



76 February 1981 © BYTE Publications Inc 



ATTENTION APPLE & PET OWNERS 

MARCH 10,1981 

will mark the beginning of a new era in Microcomputer Software. A Relational 
Database Management System and an Intelligent Accounting System will then 
be available for Apple and PET users. 



Request Thinker 



Relational Query System for Management 

• Most powerful database scheme known 

• First TRUE relational database management system (ALL records 
are cross-indexed to ALL other records!) 

• Multikeyed random access (No sorts ever) 

• Sophisticated screen formatting & data entry (Like on IBM 3270!) 

• Full report writer 

• Extensive search capabilities 

• Automatic data compression for increased disk capacity 

• Records up to 4K in length 

• Interfaces to Visicalc", The Source'", and word processors 

• Much more! 



Accounting^ Software that thinks for itself. 

EASY TO USE— 

Fully Integrated Accounting System 

The THINKER'" consists of 7 comprehensive interactive modules, 
with all transactions applied immediately and the results are 
instantaneously accessible. They are: 

• ACCOUNTS RECEIVABLE • ACCOUNTS PAYABLE • SALES 
ORDER ENTRY . PURCHASE ORDER ENTRY • INVENTORY 
CONTROL • GENERAL LEDGER • MAILING LIST 



FLEXIBILITY— 

Software That Grows With Your Business 

The THINKER" utilizes the D YNAF1LE'" Multi-Keyed Fil Allocation 
Scheme which dynamically manages file length and records to meet 
the businessman's needs and will automatically extend itself to work 
on hard disks without any program modification. No disk space is 
wasted because the system automatically recaptures space when 
records aredeleted. DYNAFILE'" utilizes a sophisticated indexing 
scheme, allowing direct access to any record- Machine language 
programming insures DYNAFILE*" speed, reliability, and integrity 



SUPER KRAM 



Now With Multi-Key Capabilities For Apple & Pet 



by Ken Gerrnann 



Since KRAM™ was introduced in 1 979 it has fast become known as the quickest 
and most powerful access method for serious Apple and Pet users. Now, after 
hundreds of requests we have added MULTI-KEY, MULTI-INDEX, functions, 
as well as increasing processing speed. 



IBM/370 users have VSAM (Virtual Storage Access Method} to 
provide fast, flexible keyed-access to their data. Now SUPER KRAM 
(Keyed Random Access Method), from United Software of America, 
gives Apple and Pet users the same flexibility, substantially 
increasing the processing power of the Apple and Pet. 

Until SUPER KRAM the only "random access" capability in the 
Apple and Pet consisted of a crude form of "relative record" 
processing. While this is usable for very simple applications, it (alls 
far short of the needs of today's business and analytical 
applications. Using SUPER KRAM records may be processed by 
any one of multiple "Key" values, which may consist of any kind of 
data: numbers, letters, special characters, etc. Even Apples's long- 
awaited DOS 3.3 doesn't have anything like this!! 



KRAM™ 2,0 Only $99.95 
SUPER KRAM™ Only $175 



KRAM™ 2.0 Regular Features 

• Written in 6502 machine code 
Basic compatible 

• Create/Open a dataset 

• Put record by key 

• Add & delete records by key 

■ Get any record by Full/Partial key 

• Access by any key in as littie as .2 sec. {.1 sec. with Corvus disk) 

• Supports multipledisks 

• Read next or previous record 

• Dynamic space allocation 

• Dynamic space reclamation 

• Dynamic index compression 

■ Files never need reorganization 

■ Compatible with language systems 



SUPER KRAM'S™ Added Features 

• MULTIKEY SUPPORT — Allowing simultaneous access to a 
KRAM file by more than one key field. 

• HI-SPEED READ— This feature allows increased I/O speed up to 
60% faster during processing of SUPER KRAM read next, read 
previous, put and delete requests. 

• IMPROVED INDEX ARCHITECTURE — Allowing faster index 
searchers and more efficient disk space utilization. 

• INTEGRATED BASIC COMMANDS — Allowing SUPER KRAM" 
commands to be coded in-line with Basic, providing easier usage 
ol KRAM than ever before. 

• USER-SPECIFIABLE BUFFER POOL — Allowing the user to 
specify how many KRAM files are allowed open at one time; will 
support any number of KRAM files. 

• LOGICAL RECORDS (KEYS MAY BE NON-UNIQUE)— Records 
added to the KRAM f iies are immediately accessible by any of the 
defined keys for the file (Automatic Upgrade). 

• KRAM 2.0 files are totally compatible with SUPER KRAM 







750 3RD Avenue, 

New York NY 10017 

(212) 682-0347 Telex 640055 



UNITED 
SOFTWARE 
OF 
AMERICA 



Look for the RED-WHITE-BLUE 
United Software Display at your local 
computer dealer, or send check or 
moneyorder, plus $3.00 shipping to: 

DEALER INQUIRIES INVITED 

KRAM is a trade mark of United Software of America. 








Photo 1: Sample runs of RMS Spectrum Plot, 
analysis of the sound. 



The program "plays" an arbitrary bit pattern while displaying a power-spectral 



the program. Try to discover which 
bit patterns are indistinguishable to 
the ear; see which ones you like best. 
(My favorite is 00101101, which has 
no even harmonics and sounds rather 
like a clarinet.) 

Distinctive Voices 

The bit patterns that produce 
distinct frequency spectra are the 
basic building blocks for generating 
shift-register-type music. You can 
certainly find all seventeen different 
8-bit voices by trial and error or long 
and tedious searching, but such an 
approach becomes much more dif- 
ficult as the number of bits increases. 
In any case, there is a better way to 
find the set of interesting bit patterns: 
use a computer! The program Music 
Generator (listing 2) uses a technique 
that is simple, yet interesting, and ap- 
plicable to many other problems. 

In setting up the problem of finding 
all distinct voices, the first thing is to 
determine how two bit patterns can 
be "equivalent." (This is involved 
with the mathematical concept of a 
group, and is actually a good intro- 
duction to that subject.) First, it is ob- 
vious that patterns like 00000001 and 
00001000 and 10000000 are all equiv- 
alent since they look the same (a 
single 1 and seven 0s) once they've 
started cycling around in the shift 
register. Similarly, 00101101 and 
10100101 are equivalent: the second 
pattern results from applying five 
rotate-left operations to the first. We 
can call the operation which takes the 
leftmost bit of a bit pattern and 
moves it to the right end ROL for 
rotate-left. Any patterns which can 
be converted into each other by a 
series of ROL operations are equiva- 
lent. 



But there are other ways in which 
two bit patterns can be equivalent. 
Consider the patterns 11111101 and 
00000010. If you graph these pat- 
terns, you can see that the waveforms 
to which they correspond are exactly 
the same, except for a shift of the 
zero-voltage level and a change of po- 
larity. The power spectra of these 
patterns are also the same, except for 
the zero-frequency component which 
the ear can't hear and which isn't 
plotted by RMS Spectrum Plot. (The 
zero-frequency component is just the 
average of the bits, eg: V 8 for the pat- 



tern 11111101.) Since these patterns 
are the same as far as the ear is con- 
cerned, they should also be called 
equivalent. In binary arithmetic, the 
relation between these patterns is that 
each is the l's complement of the 
other: all Is are changed to 0s, and 
vice versa. Since the l's complement 
of a binary number / is just 
11111111-/ (if / has 8 bits), it's easy to 
program in BASIC. We can call this 
operation INV for inverse, and add it 
to the list of operations that trans- 
form bit patterns into other, equiva- 
lent patterns. 



Listing 2: Music Generator for the PET. When used to generate music waveforms, this 
program will produce audibly distinct tones based on 8-bit patterns in the PET's shift 
register. Qualities are constantly modified through the application of symmetry opera- 
tions (inversion, rotation, etc) to produce interesting variations. 

10 REM BIT PATTERN GENERATOR (C) 1979 MARK ZIMMERMANN 

20 DIM V%(7): REM ARRAY FOR BIT PATTERN DISPLAY 

1 00 FOR I = 1 TO 127 STEP 2: REM TRY ALL POSSIBILITIES THAT DO NOT OBVIOUSLY 
FAIL 

200 Z = I: FOR K = 1 TO 7: GOSUB 5000: REM ROTATE BITS OF Z LEFT 

220 IF Z<I GOTO 1000: REM REDUCED TO A PREVIOUS CASE IF Z<I 

240 NEXT K: REM PASSED FIRST TEST IF REACH HERE 

300 X = 255 - 1 : REM INVERT BIT PATTERN ( 1 's COMPLEMENT)— X > I SINCE LOOP WAS 
1 TO 127 

320 Z = X: FOR K= 1 TO 7: GOSUB 5000: REM ROTATE BITS 

340 IF Z<I GOTO 1000: REM REDUCED TO PREVIOUS CASE... 

360 NEXT K: REM IF HERE, PASSED SECOND TEST 

400 GOSUB 6000: REM REVERSE BIT ORDER OF I, RESULT RETURNED IN X 

500 IF X<I GOTO 1000: REM FAILED AGAIN 

600 Z = X: FOR K = l TO 7: GOSUB 5000: IFZ<IGOTO 1000 

620 NEXTK 

660 Z = 255-X: FOR K= 1 TO 7: GOSUB 5000: IF Z< I GOTO 1000 

680 NEXT K: REM IF HERE, A SUCCESS! ! ! ! ! 

800 X = I: FOR K = TO 7: V%(K) = X-2*INT(X/2): X = INT(X/2): NEXT K: REM 
GENERATE BITS 

900 PRINT I;TAB(10);: FOR K = 7 TO STEP - 1: PRINT V%(K);: NEXT K: PRINT 

1000 NEXT I 

2000 GOTO 9999 

5000 REM ROTATE BITS OF Z LEFT 

5020 Z = 2*Z: IF Z> 255 THEN Z = Z-255 

5040 RETURN 

6000 Y = I: X = 0:FORK = 0TO 7: X = 2*X: IF Y< >2*INT(Y/2) THEN X = X+ 1 

6020 Y = INT(Y/2): NEXT K: RETURN: REM RETURN WITH X THE REVERSED VERSION OF 

I 

9999 END 



78 February 1981 © BYTE Publications Inc 



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I've only been able to think of one 
more symmetry operation to apply to 
bit patterns. (If you find others that 
leave the voice that the ear hears un- 
changed, please let me know.) This 
final operation is to reverse the bit 
order. For example, reversal changes 
11010000 into 00001011. Physically, 
reversal corresponds to playing a bit 
pattern backwards, or to reversing 
the flow of time. I abbreviate this 
operation REV. 

Now there are three symmetry 
operations: ROL, INV, and REV. 
Applying any one of them to any bit 
pattern leaves the sound that the ear 
hears unchanged. By repeatedly 



applying these operations, it's easy to 
discover sets of bit patterns that 
change into each other (the patterns 
00110011, 01100110, 10011001, and 
11001100 make up one such set). 

How does this theoretical know- 
ledge help you to determine which bit 
patterns are distinctive voices and 
which are redundant among the 256 
possibilities? A crude way would be 
to apply various combinations of 
ROL, INV, and REV to a candidate 
pattern, and consider it new if it is 
never transformed into an already- 
known or old pattern. A slightly 
better method would be to systemati- 
cally apply a series of the symmetry 









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February 1981 © BYTE Publications Inc 



Circle 46 on Inquiry card. 



operations that would guarantee that 
no possible transformations were 
missed. For example, it's clear that 
you need never apply more than 
seven consecutive ROL operations to 
a pattern, since the eighth application 
brings you back to the original 
pattern. It's also clear that applying 
INV (or REV) twice in a row makes 
no sense, since it just flips the bits 
back again. There are many possible 
sequences of operations that will find 
all possible transformations of a 
pattern. One simple sequence is: ROL 
seven times, INV, ROL seven times, 
REV, ROL seven times, INV, and 
ROL seven times. After each opera- 
tion, a potentially new equivalent bit 
pattern is produced. Applying the 
sequence to the pattern 00001011 will 
generate all thirty-one other equiva- 
lent patterns, with no repetition; 
applying it to a pattern like 01010101, 
which has only one equivalent 
(10101010), will, of course, produce 
many repetitions. 

The program of listing 2 essentially 
goes through this process in order to 
find the set of seventeen distinct 
voices, but with a few refinements to 
speed it up. First, the program works 
exclusively with the decimal number 
corresponding to each bit pattern, not 
with the pattern itself. This allows the 
program to use simple BASIC arith- 
metic operations to perform ROL, 
INV, and REV. Only when a number 
is discovered to be a new voice is it 
converted into a bit pattern for dis- 
play. Second, no time is wasted in 
checking even numbers, or numbers 
greater than 127. Every even number 
corresponds to a bit pattern ending in 
a 0, and a single rotation right (or 
seven rotations left) will always pro- 
duce a pattern corresponding to a 
smaller binary number. Any number 
greater than 127 can always be re- 
duced to a number less than 127 by an 
INV operation. Third, Music Gen- 
erator doesn't bother storing a list of 
already-discovered old patterns with 
which to compare the result of each 
transformation. Instead, it uses a neat 
yet trivial mathematical trick, one 
that should be part of every alert pro- 
grammer's repertoire. Let me intro- 
duce it to you with a short story: 

An engineer, a physicist, and a 
mathematician are taking an intel- 
ligence test. Each is led, separately, 
into a room containing a table and a 
stove. On the table there is a pitcher 
of water, a kettle, and box of tea. 

Circle 47 on inquiry card. * 



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PRV 


1A 


3A 


12A 


50A 


125A 


240A 


100 


.06 


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.35 


.90 


.3.70 


500 


200 


.07 


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1.30 


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.11 


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800 


.15 


.35 


1.00 


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1000 


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.45 


1.26 


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Each test subject is asked to make a 
pot of tea. 

The engineer fills the kettle with 
water from the pitcher, puts it on the 
stove, brings the water to a boil, and 
makes the tea. When the physicist en- 
counters the same situation, he thinks 
for a while, puts the tea into the cold 
water, etc, but eventually hits upon 
the solution. The mathematician 
takes a little longer, but finally he too 
solves the problem. 

For the second part of the test, each 
subject is led into another room. In 
this room, again, there is a stove, a 
table with a pitcher of water, and a 
box of tea. The difference is that the 
tea kettle is now sitting on the floor. 

When the engineer enters the room 
and is asked to make tea, he picks up 
the kettle, fills it with water, puts it 
on the stove to boil, and so on, as 
before. The physicist stops and thinks 
for a short time, then figures it out, 
and does essentially the same. 

But the mathematician, as soon as 
he encounters the puzzle, simply 
takes the kettle from the floor and 
sets it on the table. Then he stops. He 
has reduced the problem to a previ- 
ous case — one he has already solved. 
As far as he's concerned, nothing 
more need be done. 

This trick of reducing a problem to 
a previous case may be funny or ob- 
vious, but it's also exceedingly valu- 
able in computing, and in other 
fields. When calculating the factorial 
function n\ =n X (n-l)X(n-2)X ... 
X 3X2 XI, once you know how to 
calculate n\ you can easily get (« + l)I 
by reducing the calculation to a 
previous case. When trying to find 
the prime factorization of the num- 
bers from 1 to n, once a single factor 
of a number is found, no more work 
need be done since the remaining 
number has already been factored, 
and is therefore a previous case. 
There are many other examples. 

Music Generator uses this "reduc- 
tion to a previous case" technique. 
After each transformation of a can- 
didate bit pattern, the result is 
checked to see if it is smaller than the 
original candidate under considera- 
tion. If it is smaller, you know that it 
has been previously handled, and the 
program immediately skips on to the 
next candidate (specifically, it 
branches to line 1000 which is a 
NEXT I statement). By starting with 
the smallest candidate, 00000001, and 
working upward, the program pro- 
duces a complete list of all the 



82 February 1981 © BYTE Publications Inc 



Circle 49 on Inquiry card. 



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card 225 

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CCA DATA 
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THE CONTROLLER General 
Business System 519 

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ment & Inventory system 199 

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Processor 65 

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EVALUATOR 45 

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Volumes 1-5 w/manuals . . 30 
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DISASSEMBLER 75 

APPLE DOS TOOL KIT 65 

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Management System .... 23 
ADVENTURE by 

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by HAYDENICass.) 27 



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APPLE PLOT.. .. 60 

TAX PLANNER 65 

SARGON II Chess 

on Diskette 32 

TRILOGY OF GAMES 27 

SPACE GAME ALBUM 38 

SPACE INVADER (Cass.). . . 18 
SPACE INVADER (Disk.). . . 23 
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8080Simulator 17 

FORTH MbyPROGRAMMA 

SOFTWARE 45 

SINGLE DISK COPY 

ROUTINES 17 

APPLEBUG DEBUGGER. . . 27 
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The CORRESPONDENT 35 

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COMPUTER CHESS 35 

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MUSIC COMPOSER 49 

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ANADEX DP-8000 775 

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Circle 50 on Inquiry card. 



Choices for actual locations: 



P = 

Q = 2 
R=2 
RNDPTR = DD (hexadecimal) 
RNDNUM = DE (hexadecimal) 
D = EC (hexadecimal) 
V = F3 (hexadecimal) 
N =F4 (hexadecimal 



;P,Q,R occupy "USR(X)" storage area! 



-.random numbers in PET's RND(X) location 
;in PET's "EOT character" area 

;V,N in tape buffer pointer area 



Ml =033 A (hexadecimal) = 826 (decimal) 

M2 = 036C (hexadecimal) = 876 (decimal) 

I =03D8 (hexadecimal) = 984 (decimal) 

Music table occupies 03D9 thru 03E0 (hexadecimal) = 985 thru 992 (decimal). 

INTR VLTAB = 03E1 = 993 

Interval table occupies 03E1 thru 03E8 (hexadecimal) = 993 thru 1000 (decimal). 

NOT ETA B = 03E8 = 1000 

Note table occupies 03E8 thru 03F F (hexadecimal) = 1000 thru 1023 (decimal). Note overlap with interval table. 

Contents of tables: 

01234567 89ABCDEF 

03E0: — 00 00 04 F9 07 F5 OC FB ED EO D3 C7 BC Bl A7 

03F0: 9D 94 8C 84 7C 75 6E 68 62 5C 57 52 4D 49 45 41 



Algorithm Description 

Ml. (Initialize) Point PET hard- 
ware interrupt vector to M2. 
SET Q, R, and N to 8; zero 

music table 1(1), 1(2) 1(8). 

Set P, V, and D to 1. 

M2. (Interrupt enters here) Decre- 
ment note duration counter D; 
if result is nonzero, go to 
PROCEED below. 

M3.(Next note) Reset D to 4 (or 
other chosen length of note to 
be played, in units of y 60 sec- 
ond). Look up interval I(P) 
and add that to note N, stay- 
ing in allowed range (0 to 23). 
Decrement pointer P; if result 
is nonzero, go to step M6. 



M4. (A measure of eight notes has 
been completed) Reset P to 8. 
Decrement voice V (bit pattern 
making sound) by 4 (or other 
choice), and if result is 
negative, reset V to maximum 
(=85). Change voice of note 
(POKE 59466, V). If counter Q 
is nonzero, invert interval I(Q) 
by negating value of I(Q), 
decrement Q and go to step 
M6. 

M5.(All eight inversions have 
been completed) Reset Q to 
8. Replace interval I(R) by 
another "randomly" chosen 
interval from the allowed 
table of intervals (in musical 
notation, table contains 
thirds, fifths, octaves, etc). 



Decrement R, and if R 
becomes 0, reset R to 8. 

M6. (Play next note) Play new 
note NOTETAB(N). looked 
up in notetable. (POKE 59464, 
NOTETAB(N).) 

PROCEEDJump to PET's normal 
interrupt-handling routine 
(E685). 

To use Tiny Timesharing Music 
give command SYS(826) to turn 
music on and off. (You must turn 
it off before tape operations, 
since the PET uses the same inter- 
face chip when reading/writing 
tapes ) 



distinct-tone-quality bit patterns. 
(Patterns 00000000 and 11111111 are 
not included, since they're inaudible.) 
When written as binary numbers, 
the legal (irreducible) bit patterns 
have some interesting resemblances 
to the set of prime numbers (numbers 
that have no positive factors except 
themselves and 1). They are quite 
dense at the lower end of the range of 
available numbers, but become fewer 
and farther between as the candidate 
numbers get larger. There's a simple 
reason for that: if a large number is 
chosen at random, it's likely that 



some combination of the operations 
ROL, INV, and REV will be able to 
transform it into a smaller number, a 
previous case. (Similarly, there is a 
good chance that a large integer 
chosen at random has a factor among 
the many smaller integers between 
itself and 1, so the density of prime 
numbers decreases.) However, even 
as you go to higher numbers, an occa- 
sional pair of distinctive bit patterns 
appears, separated by a single even 
number. Among the 8-bit musical 
patterns, the pair 43 = 00101011 and 
45 = 00101101 is a good example of 



such a "musical-pair"; if you look at 
16-bit patterns, which potentially 
range from 1 thru 65535, pairs such as 
11059, 11061 can be found. Prime 
numbers can also come in such pairs; 
as far as I know, however, there is no 
proof that an infinite number of 
prime pairs exist. There may be other 
analogies between the theory of 
primes and the distinct-voice musical 
bit patterns — I'd be interested in hear- 
ing about your discoveries. 

From Tones to Music 

I began this discussion with a look 



86 February 1981 © BYTE Publications Inc 



Ml: 



LOOP1: 



M2: 
M3: 



OVER1: 



OVER2: 



M4: 



OVER3: 



M5: 



M6: 



PROCEED: 



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LDA #0 

STA I,Y 

DEY 

BNE LOOP1 

INY 

STYP 

STY V 

STYD 

CLI 

RTS 

DEC D 

BNE PROCEED 

LDA #8 

STAD 

LDXP 

LDA I,X 

CLC 

ADC N 

BPL OVER1 

ADC #$0C 

BPL OVER2 

CMP #$18 

BCC OVER2 

SBC #$0C 

STAN 

DECP 

BNEM6 

LDY #$8 

STYP 

LDA V 

SEC 

SBC #4 

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LDA #$55 

STA V 

STA $E84A 

LDXQ 

BEQM5 

SEC 

LDA #0 

SBC I,X 

STAI.X 

DEC Q 

BPLM6 

STYQ 

INC RNDPTR 

LDX RNDPTR 

LDA 0,X 

EORRNDNUM 

STA RNDNUM 

AND #$7 

TAX 

LDA INTRVLTAB.X 

LDXR 

STA I,X 

DECR 

BNEM6 

STYR 

LDXN 

LDA NOTETAB.X 

STA $E848 

IMP $E685 



.'disable interrupts during changeover 

;PET hardware interrupt vectors thru $0219,021A 

;changes normal contents, $85, to $6C, and vice versa 



.'changes $E6 to $03, and vice versa 

; = 59467, auxiliary control register 

;change $00 to and from $10 (free-running shift out) 

;now initialize page zero music counters 



;clear out music table in 1+ 1 thru 1 + 8 



; initialize more page zero counters 



;re-enable interrupts 

;this is where interrupt vector was changed to point to 

;keep playing same note for duration D 

;value may be changed to vary tempo. . .4 thru 16 is nice. 



;fetch next interval from music table to be added to note N 



;if displacement made N negative, add 12 to move up an 

octave 

;always take the branch (this could be omitted to save 2 

bytes) 

;make N less than 24 

;subtract an octave to get in range 

;move note pointer back one 
;go to play note if nonzero 

;reset pointer P 

;change voice (tone quality, bit pattern shifted out) used 
;change this number 4 if other patterns are desired 

;reset to maximum interesting pattern ( = 85 decimal) 

; = 59466, shift register 

;branch if it's time to change an interval randomly 

.'invert an interval (negate it) in music table 



;always take branch 

;reset Q to 8 

;move pointer forward 

;get a "random" number from page zero 

;mix its bits with previous "random" ones 

;save them for future mixing 

;mask out bits to get a "random" # in range thru 7 

,'prepare to take an interval from INTRVLTAB table 

;find out which music table entry to alter 
linsert new "random" interval 



,'reset R to 8 if necessary 
;find what note to play 

; =59464, controls shift rate 

;return to normal interrupt-handling chores 



Listing 3: Tiny Timesharing Music. This 
interrupt-driven program runs concur- 
rently with other PET programs, and uses 
their changing data to update its tone- 
parameters (see the text box "Algorithm 
Description"). The interrupt occurs every 
y 60 of a second to cause the PET to check 
the keyboard for closed keys. 

at Fourier analysis, and have 
wandered through a bit of group 
theory in looking at shift-register- 
generated tones and what they sound 
like. I'd like to close with a practical 
application of this material. 

I often run fairly long programs, 
and it can be boring to stare at a static 
video screen, waiting for the results 
to appear. Then, too, I sometimes 
become paranoid and suspect that the 
machine has crashed, leaving me to 
wait forever. Well, I thought, why 
not put a little musical theory to 
work? Why not have music while I'm 
waiting for the programs to finish? 

The more I thought about it, the 
better the proposal sounded. The PET 
is always interrupted sixty times per 
second, to scan the keyboard and up- 
date the internal clock. (This happens 
as long as the interrupt-disable flag 
hasn't been set in the 6502 micropro- 
cessor; the flag is rarely set during 
normal operation.) At each interrupt, 
the microprocessor branches to the 
address stored in memory locations 
0219, 021A. Normally, these ad- 
dresses point to hexadecimal location 
E685, but by changing the address 
pointed to, I could take control once 
every V 60 second — and play music! 

The requirements that a good 
interrupt-driven music-generation 
program must meet are rather severe: 

1. It must produce interesting 
musical patterns, neither too 
repetitious nor too chaotic. 

2. It must be fast so that the main 
program does not slow down ap- 
preciably while music is playing. 

3. It must be small; the main pro- 
grams must not be squeezed out of 
memory or restricted by the music 
generator. 

The program shown in listing 3 
resulted. Tiny Timesharing Music 
meets the third requirement by occu- 
pying only the memory at locations 
826 thru 1023 (second cassette 
buffer), plus five locations on page 
zero. It satisfies the second require- 
ment by being fast; running at normal 



February 1981 © BYTE Publications Inc 87 





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speed it uses about 18 /ts every % 
second — only 0.1% of the machine's 
time. (Changing notes at top speed 
uses less than 0.4% of the time.) As 
for whether or not it meets the first 
criterion, you'll have to judge for 
yourself: "interesting" is in the ear of 
the beholder. I enjoy it, although it's 
certainly nowhere near Bach's Art of 
Fugue... then again, nothing is. 

The algorithm description which 
accompanies this listing (see the text 
box "Algorithm Description") should 
make its method of operation clear. 
The theory of music is beyond the 
scope of this article (and me!), but in 
brief, the program works as follows: 
first it generates eight intervals, 
chosen from a musically "nice" set of 
possibilities (see Arthur Benade's 
book, and other references, for more 
details). Beginning with a base note, 
eight notes are played, each related to 
the previous note by one of the 
chosen intervals. After a measure of 
eight notes is completed, the bit pat- 
tern (voice) being used by the shift 
register is changed, one of the eight 
intervals is inverted, and another 
measure is played. (Inversion simply 
amounts to a sign change: an interval 



of +7 (a fifth) is inverted to —7.) 
After all eight intervals have been in- 
verted, one is replaced by a new, ran- 
domly-chosen interval, and the whole 
process is repeated. The "random" 
numbers are influenced by the con- 
tents of page zero, so if the user is do- 
ing something, or running any pro- 
gram, the musical patterns produced 
will never repeat for long. 

As always, I will be delighted to 
learn of any improvements that 
readers make in this musical pro- 
gram. The best way to test ideas for 
musical pattern generation is to run 
them as non-timeshared BASIC pro- 
grams. Then they're easily modified 
and debugged, and if they sound 
good, they can be coded in assembly 
language. In Tiny Timesharing Music 
as presently written, it's easy to 
change the tempo of the notes: just 
POKE 881,X where X is the length of 
the notes in units of V 60 second 
(values of X between 4 and 16 seem to 
work best). The contents of memory 
location 918 govern the changes be- 
tween one voice and the next: the 
number there (and in location 922) 
may be changed to vary the sequence 
of bit patterns used. The table of 



musical intervals in locations 
993-1000 can be varied according to 
taste, as can the table of notes 
(1000-1023; note that one table entry 
is in common, to save space). I use a 
digital approximation to a well- 
tempered scale, but you may prefer 
another choice.! 



References 

1 .Apel, Willi and Ralph T Daniel. The Harvard 
Brief Dictionary of Music. Pocket Books, 
1960. 

2.Benade, Arthur H. Horns, Strings and Har- 
mony. Doubleday Anchor Books, 1960. 
3. BYTE magazine, September 1977. Several 
interesting and useful articles, especially one 
by Hal Chamberlin, page 62. 
4.Crawford, Frank S. Waves — Berkeley 
Physics Course, Volume 3. McGraw-Hill, 
1968. 

5.Feynman, Richard P. The Feynman Lec- 
tures on Physics, Volume 1 , lecture 50. 
Addison-Wesley, 1963. 
6. Foster, Caxton C. Programming a 
Microcomputer: 6502. Addison-Wesley, 
1978. 

7.Kinnard, J R. "Generating square waves 
with the PET," PET User Notes, Volume 1, 
Number 3. Published by Gene Beals, POB 
371, Montgomeryville PA 18936. 
8.Rabiner, Lawrence R and Charles M 
Rader, Editors. Digital Signal Processing. 
IEEE Press, 1972. 



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Programming Quickies 



Converting 
Pitch to Frequency 

Robert Katz, 248 E 90th St, #3B, New York NY 10028 

This program converts pitch to frequency and can use 
either the piano tuner's scale (based on a perfect fifth in- 
terval), or the scientific, or "just," scale (based on a 
perfect octave interval). The scales are equally tempered 
in either case. 

The program is written in RPN (reverse Polish nota- 
tion) for a Hewlett-Packard calculator. Step 8 includes a 
GTO instruction. If your calculator has labels instead of 
step numbers, use a label at steps 8, 10, 32, and 35. 

To use the program, place a number from 1 to 7 in the 
x register. This represents one of the notes from C to B in 
the 12-note scale. To indicate the standard "whole" tones, 
use a whole number (such as 1 for C, 6 for A, etc). To in- 
dicate an accidental, use an integer plus 0.5 (6.5 for A#, 
2.5 for D#). If the tones are to be in the octave of middle 
C, make sure a is contained in the y register. Otherwise, 
the number in the y register should be an integer 
representing the number of octaves above or below 
middle C. For example, 5.5, —2 represents G§, two oc- 
taves below the octave of middle C. Once the pitch has 
been entered, all you have to do is press R/S. For 
example, enter (6, 0) and press R/S. This will display 440, 
which is the pitch of A in the octave of middle C. 

The formula is: 

261.25 X (-3T ) Pl+P2 



Listing 1: A program to convert pitch to frequency. This listing 
is in the RPN (reverse Polish notation) for a Hewlett-Packard 
calculator. If your calculator uses labels instead of step 
numbers, a label must be used at steps 8, 10, 32, and 35. In a 
calculator with continuous memory, steps 15 thru 21 and steps 
24 thru 29 can be replaced with a constant recalled from 
memory. 



1 


f fixO 


20. 


q 1/x 


? 


1 


21. 


f r 


a 




22. 


x~y 


4 


2 


23. 


f r 


S 


X 


24. 


2 


6, 


5 


25. 


6 


7. 


f x<y 


26. 


1 


8 


GTO 32 


27. 




q 


i 


28. 


2 


in. 


x~y 


29. 


5 


11. 


1 


30. 


X 


17 


2 


31. 


GTO 00 (or q RTN) 


13. 


X 


32. 


1 


14. 


+ 


33. 


1 


IS. 


1 


34. 


- 


16. 




35. 


GTO 10 


17. 


5 






18. 


ENTER 






19. 


7 







WHY CIS COBOL 

LETS YOUR 

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Now, you can use a microcomputer for 
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Forms 

The FORMS utility lets you build a 
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A superset of FORMS, it eliminates the 
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Rostronics and Johnson-Laird Inc. tlntellec is a trademark of Intel Corp. *CP/M is a trademark of Digital Research Inc. 

BYTE February 1981 93 



where Pi is a power within the octave of middle C. P 2 is a 
power that will reach any octave above or below middle 
C. Steps 15 thru 21 compute the seventh root of 3 / 2 , 
which is the relationship of a semitone within the piano- 
tuner's scale, based on perfect fifths and stretched oc- 
taves. Replace steps 15 thru 21 with the twelfth root of 2 
and you will have the standard, perfect octave scale. 
When using the perfect octave scale, you may have to 
change steps 24 thru 29 to 261.63 to obtain an A 440. 
Steps 24 thru 29 are the frequency of middle C, on which 
the program is based. Note also that steps 32 thru 35 are a 
correction factor based on the half step between E and F 
in the scale.! 



BYTE's Bits 



NSF Awards 
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addition, and subtraction. 
The New York City-based 
research and development 
organization's approach 
stresses learning through 
insight and practice rather 
than rote memorization. 
Feedback from the instructor 
helps guide and refine the 
student's growing insight. 
According to Educational 
Solutions's hypothesis, 
perceptual activities, feed- 
back, and practice eventual- 
ly teach the student practical 
skills. 

Under the provisions of 
the grant, Educational Solu- 
tions must first produce a 
prototype of the course- 
ware, then test it on public 
school students. After anal- 
ysis, the courseware will be 
revised and prepared for 
distribution. 



OSU's TABS Project 

The College of Education 
at OSU (Ohio State Univer- 
sity) is busily at work on 
project TABS. The purpose 
of this project is to develop 
and disseminate curricular 
materials in which high 
technologies are used to 
teach basic mathematical 
skills such as problem solv- 
ing, estimation, and com- 
puter literacy. Funded by 
the US Department of 
Education, project TABS's 
goal is to collect and 
evaluate existing educational 
software for microcomputers 
and select the highest quality 
programs for distribution. 
The programs are to be field 
tested and distributed 
nationally. 

Individuals or groups who 
have developed mathematics 
software for the upper 
elementary-school level are 
invited to submit their work 
for possible inclusion in the 
project. To have materials 
considered, send a cassette 
tape or floppy disk with a 
printout, machine docu- 
mentation, and any related 
information to Dr Suzanne 
K Damarin, TABS Project, 
Arps Hall 202-A, 1945 N 
High St, Columbus OH 
43210, (614) 422-1257. ■ 



94 February 1981 © BYTE Publications Inc 



Circle 54 on Inquiry card. 



Free software ($50-$120 worth). Plus a cash 
rebate when you buy the programmable. 




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2 FREE modules, 2 FREE 
Pakettes with a TI-59. 

1 FREE module, 1 FREE Pakette 

with a V^^m 

TI-58C. - ^ 



Free software plus cash rebates. 

A $10rebateon aTI-58C--$25rebateonaTI-59. 




ip 



The TI-58C. An exceptional value. 

Up to 480 program steps or 60 mem- 
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U.S. suggested retail prices. * For use with TI-59 only. 



Texas Instruments 



©1981 Texas Instruments Incorporated 



INCORPORATED 



45746A 



Apple en castellano 

Tercer Medio 
presenta 
su sistema 
administrativo 

(T.M.A.) para Apple 11 

Disenado de acuerdo con los principios 
contables aceptados en todos los pai'ses 
de habla hispana. 

APLICACIONES COMERCIALES 
YCIENTIFICAS 



• CONTABILIDAD 
GENERAL 

Diario General 
Resumen del Diario 
Consulta parcial al Diario 
Mayor General 
Balance de Comprobacion 
Balance General 
Ganancias y Perdidas 
Catalogos de Cuentas 
Consultas por pantalla 



• CUENTAS 
POR COBRAR 

Catalogo de Cuentas 
Listado de Transacciones 
Antiguedad de Saldos 
Saldos por Veneer 
Relacion de Cobranzas 
Relacion de Pagos 
Estado de Cuentas 
Consultas varias por pantalla 



INVENTARIO Y FACTURACION 

CONTROL DE BANCOS 

PERT/CPM 

CUENTAS A PAGAR 

CONTROL DE COSTO DE OBRAS 

VENTAJAS DEL SISTEMA T.M.A. 

Son completamentes conversacionales. 

El chequeo de la informacion es instantaneo. 

Los reportes impresos o por pantalla guardan 

los formatos generalmente aceptados. 

Estan pensados para adaptarse a cualquier 

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53 



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Software Review 



Infinite BASIC and 
Infinite Business 

Scott Mitchell, 346 S Taylor St, Manchester NH 03103 

Infinite BASIC is a software-utility package for the 
Radio Shack TRS-80 sold by Racet Computes. The pack- 
age has a suggested retail price of $49.95, with an op- 
tional Infinite Business package available for $29.95. 

The purpose of these packages is to add extra com- 
mands to either your disk BASIC or Level II cassette 
system. Infinite BASIC adds eighty commands to your 
BASIC vocabulary, so if you thought the Level III add-on 
for your cassette system was a good deal, you'll consider 
this a steal for the same price. Level III BASIC (from 
Microsoft Consumer Products, Bellevue, Washington) 
always consumes 4 K bytes of memory, even if you use 
only one or two of its features in your program. Infinite 
BASIC lets you take only the features you want and put 
them on a system tape or disk file, thereby saving 
memory space. Also, you can place the resulting object 
code in memory anywhere you wish. These two features 
make Infinite BASIC a versatile package for both disk 
and tape users. 

Infinite BASIC — Matrix and Strings 

Infinite BASIC is the foundation of the program set. 

Text continued on page 100 





Name 


Language 


Infinite BASIC and 


Z80 machine language 


Infinite Business 






Computer 


Type 


Radio Shack TRS-80 


BASIC extension soft- 


with either disk BASIC 


ware system with in- 


or Level II cassette 


dependent application 


system 


modules 






Documentation 


Manufacturer 


Printed booklets 14 by 


Racet Computes 


22 cm (5Vi by 8V2 


702 Palmdale 


inches); for Infinite 


Orange CA 92665 


BASIC, two booklets 


(714) 637-5016 


totaling 84 pages; for 




Infinite Business, one 


Price 


booklet with 21 pages 


Infinite BASIC: 




$49.95; Infinite 


Audience 


Business: $29.95 


Business, game, and 




general programmers 


Format 




5-inch floppy disk or 




tape cassette 





96 February 1981 © BYTE Publications Inc 



Circle 55 on Inquiry card. 



But no matter what the size, they all give you increased sales, 
greater security, and lower costs. 

Choose from the VIP (315K bytes with optional add-ons uptol.2M 
bytes), the Vector 2800 (2M bytes with 91 msec average access time), 
or the Vector 3030 (32M bytes with 34 msec average access time). 

Each one gives you more disk speed and capacity than compet- 
itive models. So you can offer a less expensive system with more 
capacity than your competition, or one with much greater capacity for 
the same money. 

Our multiple configurations with transportable software do not 
lock you into one level of system. For reliability, Vector builds industry 
standards into each Economy Sized Computer. Standard software and 
components include CP/M2® operating system, Microsoft BASIC-80? 
S-100 bus, 4 MHz, Z80A processor, RS-232C serial ports. 

Our modular systems use common Vector 3 mainframes, boards, 
and printers. They save you time and money on inventory, service, 
staff, and training. Software transportability from one system to the 
next eliminates the cost of -,-. « j ^ 

rewriting or converting Economy Sized Computers 

software and data. Our now Come in small, 

advanced software develop- medium and large. 

ment tools reduce de- 
velopment time dra- 
matically. And since 
we have such a wide 
range of models, we hel p 
you make more sales. 

All this goes to 
prove one thing. 

That is, no mat- 
ter what size system 
you're building, an 
Economy Sized Com- 
puter can be a big help. 

For more infor- 
mation, write Vector, 
31364 Via Col inas, West- 
lake Village, CA 91362. 
Or call 213/991-2302. 





Economy Sized Computers 



Circle 56 on inquiry card. 



BYTE February 1981 



97 



Stack Work's 



A full, extended FORTH interpreter/compiler 
produces COM PACT, ROM ABLE code. As fast as 
compiled FORTRAN, as easy to use as interactive 
BASIC. 




SELF COMPILING 

Includes every line of source 
necessary to recompile itself. 



:: EXTENSIBLE 
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CHAMPAIGN, IL 61820 
(217)359-2112 

Technical Hot Line: (217) 359-2691 
answered only when technician is available) 





VfSA 



SuperSoft 

First in Software Technology 

*CP/M registered trademark Digital Research 



Listing 1: Sample string-manipulation program and run. Note 
that the commands are small and compact. The program in- 
itializes string AS, performs a function on it, and prints it out. 
After each printout of the modified string, AS is reset to its 
original contents and the next operation is performed. With 
each command that modifies AS, the modified string is stored in 
]$. However, it could simply be put back into AS. The program 
runs quite fast. 

I CLS 

10 GOSUB1000 

I I PRINT:PRINT"A$ = (";:PRINTA$; :PRINT")" 

20 J$ = &SLR$(A$,6):' LEFT ROTATION COMMAND 

21 PRINT'XEFT ROTATE BY 6 = (";:PRINTJ$;:PRINT")" 
30 GOSUB1000 

40 J$ = &SRR$(A$,6):' RIGHT ROTATION COMMAND 

50 PRINT"RIGHT ROTATE BY 6 = (";:PRINT]$;:PRINT")" 

60 GOSUB 1000 

70 J$ = &SLJ$(A$):'LEFT JUSTIFICATION COMMAND 

80 PRINT"LEFT JUSTIFIED = (";:PRINTJ$;:PRINT")" 

90 GOSUB1000 

100 J$ = &SRJ$(A$):'RIGHT JUSTIFICATION COMMAND 

110 PRINT"RIGHT JUSTIFIED = (";:PRINTJ$;:PRINT")" 

120 GOSUB1000 

130 J$ = &SLT$(A$):'LEFT TRUNCATION COMMAND 

140 PRINP'LEFT TRUNCATED = (";:PRINTJ$;:PRINT")" 

ISO GOSUB 1000 

160 J$ = &SRT$(A$);'RIGHT TRUNCATION COMMAND 

170 PRINT'RIGHT TRUNCATED = (";:PRINTJ$; :PRINT")" 

180 GOSUB 1000 

190 J$ = &SLS$(A$,4):' LEFT SHIFTING COMMAND 

200 PRINT"LEFT SHIFTED BY 4= (";:PRINTJ$;:PRINT")" 

210 GOSUB1000 

220 J$ = &SRS$(A$,6):' RIGHT SHIFTING COMMAND 

230 PRINT"RIGHT SHIFTED BY 6= (";:PRINTJ$;:PRINT")" 

240 GOTO240 

1000 A$ = " ABCD EF " 

1010 RETURN 

9999 END 

RUN 

A$ = ( ABCD EF ) 

LEFT ROTATE BY 6 = (D EF ABC) 

RIGHT ROTATE BY 6 = ( EF ABCD) 
LEFT JUSTIFIED = (ABCD EF ) 
RIGHT JUSTIFIED = ( ABCD EF) 
LEFT TRUNCATED = (ABCD EF ) 
RIGHT TRUNCATED = ( ABCD EF) 
LEFTSHIFTEDBY 4 = (BCD EF ) 
RIGHT SHIFTED BY 6 = ( ABCD) 



Listing 2: Program and run showing the packed-decimal 
mathematics function. The numbers must be saved into strings, 
then converted into packed decimal by the proper command. 
One may initialize precision up to 500 places; however, the 
more places you specify, the slower the operation will become. 
When the answer arrives, it is converted back to a string for 
printing or further normal mathematics functions. The precision 
of the exponent printed out in the answer is also initialized to 
either 10-" to 10" or I0" 3276S to 10 327 ". 

10 CLS:DEFINTC 

20 CLEAR2000 

30 N$ = 'T':X$ = "3994949" 

40 J = &BPRC(120,2):'SETS UP 120 DECIMAL PLACES PRECISION 

50 ' + OR -32767 EXPONENT RANGE 

60 N$ = &BCP$(N$):X$ = &BCP$(X$):'CONVERTS X$ + N$ PACKED 

DECIMAL 
70 A$ = &BDP$(N$,X$):' DIVIDES A$ BY X$ PACKED DECIMAL 
80 N$ = &BPC$(A$):'CONVERT ANSWER TO PRINT 
90 PRINT" 1/3994949= ";:PRINTN$:'PRINTS ANSWER 
99 END 

RUN 

1 A3994949 = 2.5031 6086638402642937369 1 629 1 04651 899 185696 
7385566 1 2362260444376 1 35965690675900993980 1 484324330548 
39999209001 16622264764D-00007 



98 February 1981 © BYTE Publications Inc 



wv 



.Threaded Interpretive 

Languages 




R. G. Loeliger 



Threaded languages (such as FORTH] are an exciting new class of languages. They are compact 
and fast, giving the speed of assembly language with the programming ease of BASIC, and com- 
bine features found in no other programming languages. An increasing number of people are 
using them, but few know much about how they work. Is a threaded language interpreted or 
compiled? How much memory overhead does it require? Just what is an "inner interpreter?" 
Threaded Interpretive Languages, by R. G. Loeliger, concentrates on the development of an 
interactive, extensible language with specific routines for the ZILOG Z80 microprocessor. With 
the core interpreter, assembler, and data type defining words covered in the text, it is possible to 
design and implement programs for almost any application imaginable. Since the language itself 
is highly segmented into very short routines, it is easy to design equivalent routines for different 
processors and produce an equivalent threaded interpretive language for other development sys- 
tems. If you are interested in learning how to write better FORTH programs or you want to design 
your own powerful, but low-cost, threaded language specific to your needs, this book is for you. 



Din i a 



This and other BYTE/McGraw-Hill 
books are available from BYTE 
Books or your local computer store. 

Please send 



ISBN 0-07-038360-X 
Price $18.95 



copies of Threaded Interpretive Languages 



Company 



Street 



City 



State/Province 



Code 



Call TOLL FREE: 800-258-5420 
or Mail To: 



Bill I'M 70MainSt 



Peterborough, NH 03458 



Check enclosed in the amount of $ 

_ Bill Visa G Bill Master Charge 

Card No 

Exp. Date 

Add 75<r per book to cover postage and handling. 
Please remit in U.S. funds or draw on a U.S. Bank. 



Text continued from page 96: 

The extra commands available handle functions that, if 
done as a routine in standard BASIC, would take up to 
fifty times longer. The commands provide capabilities for 
matrix and string manipulation, graphics, and data com- 
pression. 

There are twenty-three commands in the matrix cate- 
gory. Some of the many functions that they speed up are 
copying, scaling, solving simultaneous linear equations, 
matrix inversion, and operations on a matrix from con- 
stants or another matrix. 

The speed of these commands is far superior to conven- 
tional BASIC. For instance, if you want to invert a 10 by 
10 matrix, the command is J = &MINV(A,B,C), where A 
is the matrix to be inverted, B is the array where the in- 
verted matrix is to be stored, and C is the size of the 
matrix to be inverted (default is the dimension of A), J is 
the return argument. J is if a solution is found and —1 if 
not. The command A = &MINV(A,B,3) is certainly much 
faster to execute and requires less syntax than standard 
BASIC commands. For another example, suppose you 
want to multiply matrix A by matrix B. This is performed 
by the simple statement J = &MELM(A,B). All matrix 
commands are of similar format, execution time, and 
simplicity. 

There are fourteen string-compression routines, which 
are extremely useful for compressing data for increased 
storage efficiency. However, you must know the type of 
data with which you are dealing and exactly what you in- 
tend to do to the data in the program. You can compress 
or expand in 4-, 5-, 6-, or 7-bit formats. You can use this 



in random-file formats but not in sequential files (since 
some control characters may be in the data). You can also 
convert data to lowercase or uppercase and remove 
multiple characters. 

There are fourteen string-manipulation commands 
provided, and they handle left and right character shift- 
ing and rotating, justifying, and truncating. You can also 
invert a string, sort a string (multiple-key sort), delete a 
substring, pack string text, and more. (See listing 1, page 
98, for an example.) 

The graphic commands allow drawing and erasing 
lines between any two coordinate points. Four com- 
mands allow scrolling of the screen up, down, left, or 
right. There is no wraparound feature, so scrolling up 
and down will result in a loss of what was at the top or 
bottom of the screen. These commands can best be used 
to improve screen presentation of data, and fast execu- 
tion means little time is lost. 

Other available commands include the writing of 
matrix data onto tape and the transfer of string and 
variable arguments to a subroutine in the program and 
back again. There are decimal-to-hexadecimal conver- 
sion commands. 

Infinite Business 

Infinite Business is an add-on package giving twenty 
commands that, among other things, control a printer, 
provide multiple-precision mathematics, search string ar- 
rays for matching elements, and provide hash number 
generation. (The package needs Infinite BASIC before it 
will work.) 



ATTENTION ALPHA MICRO AND MPM USERS: WE HAVE THE MISSING LINK 

Micro Pathways introduces the ZSIO, a four channel RS-232 interface and Real Time Clock board. Applications include 
Multi-User data processing and high speed telecommunications. The ZSIO board is capable of handling asychronous and 
sychronous byte oriented protocals such as IBM BISYNC and sychronous bit oriented protocals such as HDLC and IBM 
SDLC. 

For Alpha Micro users it is an ideal high speed communicationsboard as well as a four channel RS-232 upgrade. MPM users 
can enjoy the convenience of having the Real Time Clock and four serial channels all on one board. 

The ZSIO can be totally interrupt driven with no additional hardware to process restart instructions or interrupt vectors. 
Additional features include programmable baud rates from 75 to 19.2 k, solder less modem direction jumper areas and daisy 
chain capabilities to any number of boards. The ZSIO board conforms to the IEE-696 (S-100) standard bus interface. Full 
documentation includes users manual, theory of operation, schematic and extensive application notes. 



ZSIO board complete with 
documentation, RS-232 cables and 
mounting hardware $599.00 

ZSIO with Alpha Micro interface 

drivers $899.00 

ZSIO manual (credited upon board 
purchase) $ 25.00 

Dealer inquiries welcome 

Micro Pathways 

21162 Lorain Road 

Fairview Park, Ohio 44126 

216-333-8864 




100 February 1981 © BYTE Publications Inc 



Circle 58 on inquiry card. 



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Circle 59 on Inquiry card. 



I found the automatic page headings and pagination to 
be the most helpful feature in the printer category — just 
define the header or footer and run the program. This 
feature can be turned on or off and reset within the pro- 
gram. 

I have found that packed-decimal mathematics is very 
interesting to most people who have Infinite Business. 
With it, they can add, subtract, multiply, and divide with 
up to 500 significant places of precision. I would have 
liked to have seen some more mathematics functions here 
such as squares, square roots, logarithms, and other 
technical-mathematics functions. (See listing 2, page 98, 
for an example.) 

Conclusions 

• In checking over these packages, I saw two problems. 
In trying to assemble an Infinite BASIC module for use in 
low memory on tape, I set an upper limit of hexadecimal 
7FFF and the assembler bombed out. I assume this is a 
result of the assembler placing its code in the same 
memory that I had specified during the assembly process, 
thus clobbering the disk operating system. It is unfor- 
tunate that the assembler cannot make the object 
modules in high memory and save them on tape or disk. 
If this were so, the object modules could then be loaded 
into the memory locations the user specified. As it is, the 
assembler will save the object code to tape, but saving to 
disk requires typing in a cumbersome dump command. 
The assembler gives everything needed to type for this 
dump, but it would be much easier if the user did not 
have to intervene (and if the disk operating system clob- 
bering were eliminated). 

• The second problem is that the setting of memory size is 
difficult for those BASIC programmers who are not 
especially familiar with machine language. The Infinite 
BASIC documentation spends little time with examples of 
how to do this with user-created object modules. 

•The Infinite BASIC documentation is about as difficult 
to understand as the Radio Shack Level II manual. There 
are three manuals. Two are for Infinite BASIC — one 
being a general description with lots of examples, the 
other a definition of the command formats. The Infinite 
Business manual has both of these elements incorporated 
into one volume. All the information is there, but there 
are not enough examples to cover every case, so the result 
may be that the 100 available commands will be hard for 
the less experienced programmer to understand. As the 
command statements are fairly involved, frequent 
references to the manuals are necessary. 

• These packages would be of great help to the more 
skilled business, game, and general programmer who 
could best understand and make use of the available 
power. However, in comparing these to other similar 
packages, almost anyone would find enough of the 100 
commands useful to make it worth the price. ■ 

Give to the college 
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The Perfect Fit 



The Micromodem II data communications system 
and the Apple II* computer. What better combination to 
maximize the capabilities of your personal computer! 

This popular direct connect modem can transmit 
data between an Apple II and another Apple II, a 
terminal, another microcomputer, minicomputer or 
even a large time-sharing computer anywhere in North 
America. The Micromodem II has unique automatic 
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the communications possibilities between the Apple II 
and another computer or terminal. 

You can send and/or receive messages or data 
when you are out of your office, home or out of town. 
Your branch business locations can communicate with 
each other regarding inventory and other matters over 
the phone. Or you can communicate with friends 
across the country. And you can access information 
utilities like the SOURCE for various business and 
personal applications. 

The Micromodem II consists of two parts. One part 
includes the printed circuit board which holds the 
Micromodem II, ROM firmware and the serial interface. 
The board plugs directly into the Apple II providing all 
the functions of a serial interface card plus 
programmable auto dialing and auto answer 
capabilities. The on-board ROM firmware enables the 
Micromodem II to operate in any of three modes to 
perform different tasks-terminal mode, remote console 
and program control mode. 



The other part of the Micromodem II datacomm 
system is a Microcoupler which connects the 
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The Microcoupler gets a dial tone, dials numbers, 
answers the phone and hangs up when a transmission 
is over. There are none of the losses or distortions 
associated with acoustic couplers. The Microcoupler is 
compatible with any North American standard 
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The Micromodem II is completely compatible with 
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modes are available as well as speed selectable 
transmission rates of 1 1 and 300 bps. 

Why not increase your Apple ll's capabilities by 
outfitting it with the sophisticated Micromodem II data 
communications system? The Micromodem II is 
available at retail computer stores nationwide. For the 
store nearest you, call or write: 

Circle 60 on inquiry card. 



©Hayes 



Hayes Microcomputer Products Inc. 

5835 Peachtree Corners East, Norcross, Georgia 30092 (404) 449-8791 

TU Micromodem II is a trademark of Hayes Microcomputer Products, Inc. 

'Apple II is a registered trademark of Apple Computer Inc. 

The Micromodem II can also be used with the Bell & Howellcomputer. 





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Circle 61 on inquiry card. 



A Pascal Library Unit for 
the Micromodem II 



Thomas H Woteki 

814 D Street NE 

Washington DC 20002 

(MicroNet 70220,165) 



The Micromodem 

The Hayes Microcomputer Pro- 
ducts Micromodem II is a powerful 
combination of hardware and firm- 
ware that facilitates computer-to- 
computer communication. The on- 
board ROM (read-only memory) 
contains programs for originating 
and answering calls (including dialing 
the telephone) and an ACIA (asyn- 
chronous communications interface 
adapter) device for parallel-to-serial 
conversion. In addition, the accom- 
panying owner's manual provides a 
wealth of information on how to 
custom program the modem for such 
applications as repertoire dialing, 
modifying hardware defaults, and 
dumb terminal communications. All 
of the examples given are in BASIC. 

At the time I purchased a Micro- 
modem for my Apple II computer, 
Pascal software for driving it was not 
available. In fact, certain parts of the 
modem's firmware refer to locations 
and routines used by the old Apple 
monitor; these routines are accessible 
from BASIC but don't exist under 
Pascal. Having forsworn BASIC and 
being faced with the modem as my 
only non-Pascal application, I was 
determined to develop a suitable 
library of Pascal programs. With a 
little help from the friendly folks at 
Hayes Microcomputer Products (who 
are about to release their own Pascal 



About the Author: Thomas H Woteki has 
a PhD in statistics and is currently developing 
an interactive statistics package for the Apple 
II. His interests include applications program- 
ming in Pascal and systems development for 
the Apple II. 



software), and through close study of 
the manual, I was able to do just that. 

The Library Unit 

The routines are housed in an in- 
trinsic unit dubbed "micromodem" 
(see listing 1). Library units are a 
UCSD addition to Pascal; commonly 
used routines can be stored in a 
library unit that can be called by any 
Pascal program. Intrinsic units have 
the advantage that the object code of 
the unit is never entered into the code 
file of the host program, thereby 
maximizing disk storage space. A 
slight disadvantage is that the library 
containing the unit must be on-line 
(available for access) whenever the 
host program is executed. I have the 
unit stored in my system library on 
the boot disk. 

UCSD Pascal units consist of two 
major syntactical components: an 
"interface" block and an "implemen- 
tation" block. The interface block 
contains the declarations for all the 
structures available to the calling pro- 
gram, just as if they were declared in 
the global-data segment of that pro- 
gram. The implementation portion 
contains declarations used by the unit 
but not available to the host, as well 
as definitions of all the procedures 
declared in the interface. All "exter- 
nal" procedures (the independently 
assembled machine-language pro- 
grams used by the unit) must be 
declared at this point and linked in 
later. 

Our interface block begins with the 
declaration of several constants 
which correspond to the addresses of 
certain locations in the modem's 
ROM and the Apple's memory. The 



constants are appropriate to having 
the modem card in slot 2 on the Ap- 
ple's motherboard. This is the set-up 
expected by the Apple's low-level I/O 
(input/output) drivers, the BASIC 
I/O Subsystem, or BIOS. If you wish 
to install the card in another slot you 
will have to modify the addresses and 
the BIOS accordingly. 

The values "acia" and "modem" are 
the addresses of the ACIA and the 
modem control and status words, 
respectively. Both of these registers 
(actually pairs of registers) have the 
property that what is written to them 
(the control word) is not what may be 
read from them (the status word). 
Since it is important to know what 
was last written as the modem control 
word, a copy of this data is stored in 
location "modemcopy" in a portion 
of the Apple's memory. 

The value "keybde" is the address 
of the Apple's keyboard, and 
"datain" is the address where 
characters received by the modem 
can be found. The value for "outa" is 
the address of a routine in the mo- 
dem's firmware which transmits char- 
acters; this routine expects to find the 
characters in "dataout". Fortunately, 
the output routine does not reference 
any "old" monitor locations. 

The constants "resetflag" and 
"selftest" correspond to two special 
bits in the modem control word. Set- 
ting bit 3 of the word puts the modem 
into the self-test mode, wherein the 
modem communicates with itself. 
Setting bit 4 prevents the ROM from 
automatically applying default set- 
tings to the ACIA. 

The next two sets of declarations 
establish two variables, "br" and 



106 February 1981 © BYTE Publications Inc 



Circle 62 on inquiry card. 



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"md", that may assume the values 
"low" (corresponding to 110 bps [bits 
per second]) and "high" (300 bps), 
and "answer" and "originate" respec- 
tively. Following this is a set of 
declarations for boolean-valued func- 
tions that report on various aspects of 
ACIA and modem status. The inte- 
ger-valued functions "aciastatus" and 
"modemstatus" return a complete 
status report. The interface block 
concludes with a series of procedure 
declarations for setting the ACIA and 
modem control words and for per- 
forming such chores as dialing the 
phone, waiting for the other system 
to turn on its carrier, and sending and 
receiving characters. Several of these 
routines call external procedures 
declared in the implementation block. 
The implementation block begins 
with a set of declarations that 
facilitate direct-money accessing 
from Pascal. The declarations 



establish the type "freeunion", a 
variant record, and a variable 
("memory") of that type. The vari- 
able has two names (it is a free union; 
see Peter Grogono's Programming in 
Pascal, listed in the references) and 
will be interpreted differently depend- 
ing on the name used. When referred 
to as "memory .addrs" it will be 
treated as an integer, but when re- 
ferred to as "memory .pntr" it will be 
treated as a pointer to an array of the 
type "word". Thus, both the location 
pointed to and its contents can be 
manipulated from Pascal as indicated 
in the following fragment: 



VAR x:0..255; (x takes 
values from to 255) 



integer 



memory .addrs: = acia; (point to 

location acia) 

x: =memory.pntr[0]; (read the 

Text continued on page 124 



Listing 1: Library unit "micromodem" for Apple Pascal system. These routines can be 
called for use by any Pascal program, but they are intended to drive the Hayes 
Microcomputer Products Micromodem II. 

c*$lprinter:*) 

u$s+*)(* swapping requirci: for units *) 

UNIT micromodecir INTRINSIC CODE 23 DATA 245 

INTERFACE 

CONST d3t3in= -16217) C JC0A7 3 
3ci3= -16218.' { SC0A6 } 
B0dem= -1621?; £ $C0A5 3 
Keabde= -16384; C JC000 3 
outs* 

d3t,30ut= 1912J 
nodeiiiCOpy=1658; 



-15870)' C $C202 
{ $0778 
C I067A 



TYPE 



resetfl33= 9; 
selftest= 16) 

b3udr3te=( lowfhi^h )i 

oode= ( 3nswer )0ri3in3te )J 



vAR ad: mode? 

br Jb3udr3te; 

FUNCTION rin^inSIBOOLEAN) 

FUNCTION csrrier: BOOLEAN) 

FUNCTION rcvrfullIBOOLEANJ 

FUNCTION trsnseffiptyrBOOLEAN) 

FUNCTION 3Ci3error:B00LEAN) 

FUNCTION 3Ci3ststus:iNTEGER) 

FUNCTION modemststus: INTEGER) 

PROCEDURE init3ci3( word! INTEGER)) 
PROCEDURE en3bletr3nsmit) 
PROCEDURE setmode(md:node)br:b3udr3te)) 
PROCEDURE picKuP) 

Listing 1 continued on page 110 



108 Febmary 1981 © BYTE Publications Inc 



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Listing 1 continued: 



PROCEDURE dial( number !STRING)J 

PROCEDURE waitforcarrier? 

PROCEDURE hangup.* 

PROCEDURE seU.odem< word: INTEGER). 

PROCEDURE sendchsr? 

PROCEDURE getchsKUAR ch'CHAR)! 

IMPLEMENTATION 

TYPE uord=PACKED ARRAYC0..13 OF 0..255J 

freeunion=RECORD CASE BOOLEAN OF 
TRUEK addr s "INTEGER). 

FALSE'Cvslue'tword)! 

end; 

VAR »emory*freeunion J 

FUNCTION ringing.* 

C Determine whether the phone is rinsing } 
BEGIN 

Beisor y . addr s ! =M0DEM J 

ringing !=meisory.v3luet[0K128» 

end; 

FUNCTION carrier; 

( Test for presence of carrier } 
BEGIN 

memory .addr s!=acia; 

carrier!=memory .valuetCO] MOD 8'Ai 

end; 

FUNCTION rcvrfuli; 

C ChecK if ACIA receiver register is full } 

BEGIN 
memory. sddr s * = 3 c i s ! 
rcvrfull*=ODD( memory. vsluetCO]); 

end; 

FUNCTION transempta; 

C ChecK if ACIA transmitter register is empty 3 
BEGIN 

memory .3ddrs!=3cia; 

tr3nsempty!=0DD( memory. vslueKOJ DIV 2)J 

end; 

FUNCTION sciserror? 

C ChecK for ACIA error } 
BEGIN 

memory .sddr s !=3ci3j 

sciserror !=isemory . valuet[0]>3i 

end; 

FUNCTION aciastatus; 

C Determine ACIA status } 
BEGIN 
Bemory.addrs!=3cia; 
aciastatus! =memory .valuetCOIi 

end; 

FUNCTION modemstatus! 

C Determine last value written to models 3 
BEGIN 

semory .addrs!=modemcopy; 

Bodemstatus!=memory.valuet[03; 

end; 

Listing 1 continued on page 112 



110 February 1981 © BYTE Publications Inc 



Circle 66 on inquiry card. 



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Listing 1 continued: 



PROCEDURE initacia; 
C Unitialize ACIA 3 
UAR dummy? INTEGER? 
BEGIN 

senior y . addr s ?=bc i 3 i 

■e(6ory.v3luetC0]!=3f 

ttemory.v3luet[0j;=word; 

REPEAT dummy !=0 UNTIL NOT carrier 5 

end; 

PROCEDURE newmodemv3lue(newbits? INTEGER)? 

external; 

C Logical or the value last written to 
location modem (stored in modemcopy) 
with the argument? store the result 
in modemcopy and write it to models » 3 

PROCEDURE enabletransmit; 

C Turn on the modem transmitter 3 
BEGIN 
newmodemvalue(2 )i 

end; 

PROCEDURE setmodeJ 

C Set the mode and baud rate 3 
BEGIN 
newmodemvalue( 4*ord( md )+ord( br ) )i 

end; 

PROCEDURE picKu^; 

C PicK up the phone? wait for dial tone } 

UAR dummy?wait?INTEGER; 

BEGIN 

newmodemvalue( 128 )r 

C wait for dial tone3 

FOR waitt=0 TO 3000 DO dummy:=0i 

end; 

PROCEDURE dialit( number! STRING); EXTERNAL? 

C Dial the indicated numberi display the dibits 
as they are dialed 3 

PROCEDURE dial! 

C Dial the indicated number 3 
BEGIN 

URITE( 'Dialing...' )! 

dialit( number )i 

writeln? 

end; 

PROCEDURE waitforcarrierJ 

C Wait for carrier after dialing 3 
VAR datajwaitJINTEGER; 
BEGIN 
wait:=0> 

WHILE NOT csrrier AND (waiUlOOOO) DO 
BEGIN 

wait!=wait+i; 
memory. 3ddrs!=datain; 
dat3!=memory.v3luetC0]; 

end; 
end; 

PROCEDURE setmodemJ 

C Urite 3 new vslue to the modem 
control word 3 



112 February 1981 © BYTE Publications Inc 



Listing 1 continued on page 114 
Circle 68 on Inquiry card. * 



SayAhh... 




Our New graf ixPLUS™ 80-column printer 
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Introducing the newest members of our 
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Performance Plus 

The DP-9000 Series prints the full ASCII 96 charac- 
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to 16.7 characters per inch. And all characters can 
be printed double width. The print head produces . 
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with dot resolutions of 72X75 dots/inch under 
direct data source control. 

Interface Flexibility 

The three ASCII compatible interfaces (parallel, 
RS-232-C and current loop) are standard, so con- 
necting your computer is usually a matter of plug- 



it-in and print. Also standard are: a sophisticated 
communications interface for printer control and 
full point-to-point communications, DEC PROTO- 
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When you're ready for a printer (or several 
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Fullerton, CA (714) 871-0501 •Wakefield, MA (617)245-9160 • Austin, TX (512) 32V -„ 

ANADEX, INC. • 9825 DeSoto Avenue • Chatsworth, California 91311 U.S.A. • Telephone; (213) 998 

ANADEX, LTD. • Dorna House, Guildford Road • West End, Woking, Surrey GU24 9PW, England • Tel: Chobham(09905) 6333 • Telex: 858762 ANADEX < 



CROSS-COMPILE 

FORTH ! 



Nautilus Systems' Forth Cross-compiler is now in use 
by individuals, universities, and major companies 
around the world. 

OSES: 

• To produce a modified or tailored version of Forth 
on a host computer. 

• To produce Forth systems for computers that have 
none. 

• To produce applications that use the minimum 
required nucleus code. 

• To do all the above in a RDM/RAM environment. 

FEATURES: 



Written entirely in high level fig-Forth. 

Automatic forward reference to any word or label. 

Cross-compiles to any location in the host for any 

base address in the target. 

Cross-canpiles to any screen in the host for any 

base address in the target. 

Cross-canpiles vocabularies. 

Can produce headerless code. 

Can produce ramble code. 

Load map that shows address, type of symbol and 

name. The map appears in readable column format, and 

page width and length are selectable. 

A comprehensive list of undefined symbols is 

produced showing undefined CFAs, DOES? pointers, 

labels and words on a vocabulary-by-vocabulary 

basis. 



MACHINE READABLE VERSIONS FOR THE FOLLOWING SYSTEMS: 



TRS-80 
NORTHSTAR 



APPLE 
CP/M 



H-89 
LSI-11 



Each includes an executable version of fig-FORTH model 
1.0, Cross-canpiler, cross-canpilable source, 
utilities, and documentation. 
(This program is not intended for newcaners to FORTH) 

Price $150.00 (Includes shipping). Calif, residents 
please add sales tax. 



NAUTILUS SYSTEMS 

P.O. BOX 1098 SANTA CRUZ, CA. 95061 

FOR THE SERIOUS 
FORTH USER 

TRS-80 is a trademark of Radio Shack, a division of Tandy Corp. 

APPLE is a trademark of Apple Computers Inc. 

CP/M is a trademark of Digital Research. 

LSI- 11 is a trademark of Digital Equiptment Corp. 

COPYRIGHT ° 1981 NAUTILUS SYSTEMS 

HOST — TARGET 



off the modem 3 



Listing 1 continued: 

BEGIN 
•emor y . addr 5 ! =modemcop y > 
»enora.v3luetC0!It=0; 
newniodemvalue( word )> 

end; 

PROCEDURE hangup; 

C Hang up the phone? turn 
BEGIN 
seUiodent )J 

end; 



PROCEDURE sndchar J EXTERNAL; 

C Get a character from the Keaboard> 
transfer it to the modem output lo- 
cation dataout» and transmit the 
character via the modem routine 
located at ouLs } 
PROCEDURE sendcharJ 
BEGIN 
sndchar; 

end; 

FUNCTION StchartCHARJEXTERNAL; 

C Fetch the character stored in the 
inodea input location datain and 
send it to the screen. Pass the 
character as a function result. 3 
PROCEDURE Setchar; 
BEGIN 
ch! = 3tchar J 

end; 

BEGIN 
setitiodem( resetflaS ); 
END. 



Listing 2: The assembly-language programs called in the imple- 
mentation block of listing 1. These low-level utility routines are 
stored as part of a file called NAT1VECODE in a library unit, 
and may be accessed from any Pascal program. 



I I 'I I "l I V i I i i I '( I 1 1 I 1 i I I 

these routines are stored in the 
system library! 

f'0ke( value, addrs: integer)! 

f'eek( addrsi integer )t integer? 

call(addrs: integer)! 

dialit(numeer:string); 

neumodehvaluef uordt integer ) ; 

sndchar; 

gtchar; 



THOMAS H.U0TEKI 
LAST UPDATE HAY 1980 



.MACRO pop 
pla 

3TA %1 

PLA 

STA £111 



Listing 2 continued on page 116 



Hi February 1981 © BYTE Publications Ire 



Circle 69 on inquiry card. 




Circle 70 on inquiry card. 



BYTE February 1981 115 



TOLL FREE OUTSIDE CAL 1(800) 421-0347 



ocommodore 

Call for latest price on: 



8000 

iness computer 
CBM 2001 
3usiness computer 
CBM 2001 
PET 

CBM 2022 
Printer 
CBM 2023 
Printer 
CBM2040 
Dual Drive 
Floppy Disk 
CBM 8050 
Dual Drive 
Floppy Disk 




apple II & 
II plus 



Here is THE computer from NEC. 
Centronics and RS232 interfaces are 
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PRICE AND INFO., OR CALL TOLL FREE 



16K-Call 
32K-Call 
48K-Call 
toll Iree 



monitors 



9" Black and white. Only $185. 

Also available In Sanyo 

12" Black and white 
15" Black and white. 



TRS-80 



All TRS-80 Compatible Hardware 
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Huge selection for Qume, Diablo, 
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Call 1-800-421-0347. 



ill ATARI 825 
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apple cards 



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Hi-Speed Serial Interface 
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Integer Basic Firmware 
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Letter quality high speed printer, bi- 
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CALL FOR 
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Everything that 400 has plus Basic 
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4^ Bonus 8K Memory Module good till 

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Atari Program Recorder. Only $68.95 

Atari Expansion Memory 8K $89.95 
16K $159. 

% apple II 
inventory control system 

The first truly professional system 
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transaction register/audit trail, in- 
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j[ysan diskettes 

8" (Box of 10) 

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5" (Box ol 5) 
104/1 soft sector. 
107/1 10 sectors, 
105/1 16sectors $4.50 M. 




The HP-85 is a powerful 
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alete with keyboard, 
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I CalH 

Prices subject to change without 
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residents please add 6% sales tax. 
Sorry, no COD. 



£& 




m 



Micromodem 100 Ca 
Micromodem II OnlyS325 

In California Call (213) 371-1660 

/MICRO 

BUSINESS WORLD 

15818 Hawthorne Blvd., 
Lawndale. CA 90260 



Immediate response to your orders 



U.S. and International Dealer] 
uiries Invited. 



Listing 2 continued: 

.ENDM 

•MACRO PUSH 

LDA n+i 

FHA 

LDA XI 
PHA 
.ENDM 

.GLOBAL EQUATES 

PASCAL .EQU 00 

PASCALHI .EQU 01 

BI0SIN ' .EQU 0COS3 

PICSOUT .EQU 0C08B 

CONCHECK .EQU 0D681 

VIIiQUT .EQU 0D7E7 



.PR0C POKE. 2 i2 PARAMETER WORDS 

? 

5 PROCEDURE'. VALUE. ADDRS : INTEGER) 

i effect: 

V 

i VALUE IS STORED AT ADDRS 



ADDRS .EQU 02 

ADDRSHI .EQU 03 

FOP PASCAL 

LDY *00 

POP ADDRS 



."INITIALIZE Y-REG 

.SAVE ADDRESS 
,'ARGUEMENT 



PL A ,'LSB OF VALUE 

STA 8ADDRS.Y ,'STORE VALUE AT 

.ADDRS 
F1A ."DISCARD MSB VALUE 



PUSH PASCAL 
RTS 



,'BACK TO PASCAL 



.FUNC PEEK.l ,'1 PARAMETER WORD 

FUNCTION PEEK( ADDRS I INTEGER ) ! INTEGER 
5 

; effect: 

5 

5 THE CONTENTS OF ADDRS ARE 

i RETURNED BY PEEK 



ADDRS 


.EQU 02 


ADDRSHI 


•EQU 03 




POP PASCAL 




PLA 




PLA 




PLA 




PLA 




F0F ADDRS 



.DISCARD 4 BYTES 
.OF STACK BIAS 
fASSOCIATED WITH 
FUNCTIONS 

.SAVE ADDRESS TO 
iPEEK 

Listing 2 continued on page 118 



116 February 1981 © BYTE Publications Inc 



Circle 71 on inquiry card. 




The best news since CP M . . . 
customizable full screen editing 



As a serious computer user you spend much of 
your time editing, whether it be for program development 
or word processing. Make the best use of your time with 
the help of VEDIT, an exceptionally fast and easy to use full 
screen editor. VEDIT is a highly refined and proven editor 
which is easy enough for novices to learn and use. Yet its 
unequalled set of features also makes it the choice of 
computer professionals. And because VEDIT is user 
customizable, it adapts to your keyboard, hardware, 
applications and preferences. 

In VEDIT, the screen continuously displays the 
region of the file being edited, a status line and cursor. 
Changes are made by first moving the cursor to the text 
you wish to change. You can then overtype, insert any 
amount of new text or hit a function key. These changes 
are immediately reflected on the screen and become the 
changes to the file. 

VEDIT has the features you need, including 
searching, file handling, text move and macros, plus it has 
many special features. Like an 'UNDO' key which undoes 
the changes you mistakenly made to a screen line. And a 
mode which allows a programmer to enter all text in lower 
case and let VEDIT convert the labels, opcodes and 
operands, but not the comments, to upper case. The 
screen writing is almost instantaneous on a memory 
mapped display or can use your CRT terminal's editing 
capabilities. Disk access is very fast too, and VEDIT uses 
less than 1 2K of memory. The extensive 70 page, clearly 
written manual has sections for both the beginning and 
experienced user. 

Totally User Customizable 

Included is a setup program which allows you to 
easily customize many parameters in VEDIT, including 



the keyboard layout for all cursor and function keys, 
screen size (up to 70 lines, 200 columns), default tab 
positions, scrolling methods and much more. This setup 
program requires no programming knowledge or 
'patches', but simply prompts you to press a key or enter a 
parameter. 

The CRT version supports all terminals by allowing 
you to select during setup which terminal VEDIT will run 
on. Features such as line insert and delete, reverse scroll 
and reverse video are used on 'smart' terminals. Special 
function keys on terminals such as the HI 9, Televideo 
920C and IBM 3101, and keyboards producing 8 bit 
codes or escape sequences are also supported. 

New Features and Support 

The new release includes disk write error recovery, 
indent and undent keys for structured programming, and 
the ability to insert a specified line range of another file at 
the cursor position. Versions for MP/M and the Apple 11 R 
SoftCard R are now also available. 

Ordering 

Specify the CRT version, your video board or 
microcomputer, the 8080/Z80 or Z80 code version, and 
disk format required. 

Standard Package: Disk and manual $110 

Manual: Price refunded with software purchase 15 

VISA and MASTER CARD Welcomed. 
Attractive Dealer Terms. 

CP/M and MP/M are registered trademarks of Digital 
Research, Inc. Apple 11 is a registered trademark of Apple 
Computer, Inc. SoftCard is a trademark of Microsoft. 



North Star • Heath H8/H89 • SuperBrain • Apple 11 SoftCard • Sorcerer • TRS-80 Model I 
TRS-80 Model 11 • MP/M • Most other CP/M R Systems with CRT or Memory Mapped Displays 

CompuView Products Inc. 

618 Louise, Ann Arbor, Michigan 48103 • Telephone (313) 996-1299 



Circle 72 on inquiry card. 



BYTE February 1981 



117 




OS-9™ MULTIPROGRAMMING 
OPERATING SYSTEM 



/•true multitasking, real time operating system for 
/ M timesharing, software development, database, 
L m process control, and other general applications. 
This versatile OS runs on almost any 6809-based computer. 

■ UNIX™ -like file system with hierarchical directories, 
byte-addressable random-access files, and full file security. 
Versatile, easy-to-use input/output system is hardware in- 
dependent and expandable. 

■ Powerful "shell" command interpreter features: I/O 
redirection, multiple job stream processing, and more. In- 
cludes a complete set of utility commands. 

■ OS-9 Level Two uses hardware memory management 
and can address over one megabyte of memory. Also 
includes pipes and filters for inter-process data transfers. 

■ OS-9 Level One runs on systems without memory 
management hardware having up to 56K memory. 
DOS-9 Level Two $495* □ Level One $195 

BASIC09™ PROGRAMMING 
LANGUAGE SYSTEM 

Extended BASIC language compiler/interpreter with 
integrated text editor and debug package. Runs 
standard BASIC programs or minimally-modified 
PASCAL programs. 

■ Permits multiple named program modules having local 
variables and identifiers. Modules are reentrant, position 
independent and ROMable. 

■ Additional control statements for structured 
programming: IF . . . THEN . . . ELSE, FOR ... NEXT, 
REPEAT . . . UNTIL, WHILE ... DO, LOOP . . . ENDLOOP, 
EX1T1F . . . ENDEXIT. 

■ Allows user-defined data types and complex data 
structures. Five built-in data types: byte, integer, 

9 digit floating-point, string and boolean. 

■ Runs under OS-9'" Level One or Level Two. D$195* 

OTHER OS-9™ FAMILY SOFTWARE 

■ Stylograph 1 " Screen-Oriented Word Processor 

■ Interactive Assembler ■ Macro Text Editor 

■ Interactive Debugger 

BASIC09 and OS-9 are trademarks of Microware® and Motorola. UMX is 
a trademark of Bell Laboratories.* Most software is available on ROM or 
diskette in versions for many popular 6809 computers. Contact 
Microware® for specific availability. 




MICROWARG® 

Microware Systems Corp., Dept. B2 

5835 Grand Avenue, Des Moines, Iowa 50304 

(515) 279-8844 • TWX 910-520-2535 



Listing 2 continued: 




LDA *00 


.INITIALIZE 


TftY 


JY-REG 


PHA 


.PUSH MSB OF 




JRETURNED VALUE*. 




JZER0 


LDA 8ADDRS.Y 


.LOAD A WITH LSB 




5 OF RETURN VALUE 


PHA 


.PUSH ON STACK 


PUSH PASCAL 




RTS 


J BACK TO PASCAL 


.PR0C CALL.l 


! 1 PARAMETER WORD 



PROCEDURE CALLt ADDRS)? 

EFFECT t 

CALLS THE ROUTINE LOCATED AT ADDRS 
AND RETURNS TO PASCAL 

USES A FORM OF INDIRECT ADDRESSING 
SUGGESTED BY KENNETH SKIER IN THE JAN 
19S0 OF BYTE. P. 118.: 

A JSR INSTRUCTION FOLLOWED BY "ADDRS" 
ARE LOADED INTO CONSECUTIVE LOCATIONS 

^BEGINNING AT LOCATION "JUMP". CALL THEN 
JEXECUTES A JSR TO THAT LOCATION THEREBY 
JTRANSFERRING CONTROL TO THE ROUTINE 
"LOCATED AT "ADDRS". 
5 

JUHEN THE RTS IN THE DESTINATION ROUTINE 
"IS ENCOUNTERED. CONTROL IS RETURNED TO 
^LOCATION "DONE". THEN TO THE MAIN BODY 
50F CALL, THEN TO PASCAL. 







JUMP 


.EQU 02 


ADDRS 


.EQU 03 


ADDRSHI 


.EQU 04 


DONE 


•EQU 05 




POP PASCAL 




LDA *20 




STA JUHP 




LDA *60 




STA DONE 




POP ADDRS 5SAVES ADDRESS OF 




J DESTINATION ROU- 




TINE 




JSR JUHP 




PUSH PASCAL 




RTS 



,PR0C DIALIT.l 
» 
» A PROCEDURE TO DIAL THE PHONE USING 

Listing 2 continued on page 120 



118 February 1981 © BYTE Publications Inc 



Circle 73 on inquiry card. 



MULTIUSER 



III 



iiimmimim 




L 



COMPUTER 

ON S- 1 DO BUS 
DESIGNEO TO 
SATISFY A WIDE 
VARIETY OF ' 

APPLICATIONS. 

STANDARD FEATURES 

INCLUDE: CP/M . 
OPERATING SYSTEM, E4K 
EXPANDABLE, BANKSE- 
MEMORY,4MHZ 
ZSDA CPU WITH 4 SERIAL 
AND 3 PARALLEL PORTS, 
RELIABLE B" FLOPPY DISK 
DRIVES IN A STURDY ALL 
METAL CABINET. 

$ 49DO 

MP M OPTIONAL. 

;? - tii m» u registered trade marks oh t gum ke 



fpl 



r~ 



WM 



. .O. BOX 1847 SAN DIEGO, CA. 32112 
333 MISSION CENTER RD SAN DIEGO.CA. 321QB 

(714] 296-9183 






Listing 2 continued: 
THE D.C. HAYES MICROMDEM II. 

THIS ROUTINE IS CALLED BY THE PROCEDURE 

DIAL(NUMBERISTRING) 

IN THE LIBRARY UNIT MICROMDEM. 

THIS ROUTIINE ASSUMES THE MICROMDEM 
IS IN SLOT 2 ON THE MOTHER BOARD. 
IT SHARES "MODEMCOPY". 
WHICH CONTAINS A COPY OF THE MODEM 
CONTROL WORD* WITH THE LIBRARY UNIT. 



hODEh .EQU OCOA5 
MODEMCOPY. EQU 067A 

WAIT61 .EQU 9? 

UAIT3? .EQU 7A 

LOCATION .EQU 02 

LENGTH .EQU 04 

HANGUP .EQU 06 

PICKUP .EQU 07 



."SAVE THE PASCAL RETURN ADDRESS 
POP PASCAL 

.POP THE HEhORY ADDRESS OF THE 
(TELEPHONE NUMBER 
POP LOCATION 

.'INITIALIZE LOCATIONS HANGUP 




MODEL PC-10: Finger Controlled 




Desoldering 
Systems 

REMOVE ANY COMPONENT 

FROM ANY PCB 

. . . QUICKLY AND SAFELY 



MODEL PC-20: 
Footpedal Controlled 



STANDARD SYSTEM FEATURES 

■ Lightweight and Portable 

■ Internal Vacuum Pump 

■ Sodr-X-Tractor Handpiece 

■ Variable Temperature Control 




INCORPORATED 

9893 Brewers Court ■ Laurel, Md. 20810 ■ phone (301) 490-9860 



(AND PICKUP FOR 


PROPER 


DIALING 


LDA 


MODEMCOPY 








AND 


♦7F 








STA 


HANGUP 








LDA 


MODEMCOPY 








ORA 


#80 








STA 


PICKUP 








i REMEMBER HOW MANY 


DIGITS IN 


;the 


TELEPHONE 


NUMBER 




LDY 


♦00 








LDA 


0LOCATION.Y 








STA 


LENGTH 








(INITIALIZE TO 


GET 


THE 


FIRST 


(DIGIT 








LDY 


♦ 01 








NXTDIGIT TYA 










PHA 


(SAVE DIGIT 


NUMBER 


ON STACI 



LDA BIOSIN iSWTICH TO BIOS 

LDA SLOCATION.Y (DISPLAY DIGIT 

JSR VIDOUT >0N CONSOLE 

LDA BIOSOUT .'BACK TO PASCAL 

PLA (RECOVER DIGIT NUMBER 

TAY 

LDA @LOCATION,Y (GET DIGIT AGAIN 



START 



PULSE 



(CONVERT DIGIT FROM CHARATER FORM 


SEC 








SBC 


*30 






BNE 


START 






LDA 


*0A (IN CASE 


DIGIT 


IS 


(INITIALIZE X TO 


COUNT 


PULSES 


TAX 








(DIAL THE DIGIT 






LDA 


HANGUP 






STA 


MODEM 






LDA 


♦UAIT61 






JSR 


WAIT 






LDA 


PICKUP 






STA 


MODEM 






LDA 


♦WAIT39 






JSR 


WAIT 






DEX 








BNE 


PULSE 







(WHEN DONE WITH A DIGIT CHECK 
(TO SEE IF DONE WITH NUMBER 





CPY 


LENGTH 










BEQ 


DONE 










(IF 


NOT. WAIT A 


WHILE 


THEN 


GET 




(THE 


NEXT DIGIT 










JSR 


LONGWAIT 










INY 












BPL 


NXTDIGIT 








DONE 


PUSr 


1 PASCAL 










RTS 










LONGWAIT 


LDX 


♦05 








AGAIN 


LDA 
JSR 
DEX 
BNE 
RTS 


♦OFF 
WAIT 

AGAIN 









Listing 2 continued on page 122 



120 February 1981 © BYTE Publications lnc 



Circle 75 on Inquiry card. 



WHY GROWING CONCERNS PICK 
OUR FLOPPY BASED SYSTEMS 



Growing concerns require 
fresh ideas. Ideas that 
stimulate growth. Ideas 
that manage growth. Ideas 
that are designed to grow 
with the business. 

Altos Computer 
Systems, a world leader in 
single board microcom- 
puter technology, cultivates 
these ideas and delivers 
them in an attractive 
assortment of economical 
floppy disk based systems. 

Take the compact, 
portable ACS8000-2 family, 
for example. This dual 
floppy system with 64 
KBytes of RAM is perfect 
for inexpensive work station appli- 
cations such as business accounting 
and word processing. 

Altos' versatile and upgradable 
ACS8000-5 system is the solution for 
growing storage capacities. Simply 
add chips to Altos' reliable, fully 
socketed single board computer to 
upgrade to any of Altos' ACS8000-6 
hard disk or multi-user systems. 
Choose up to 208 KBytes of on- 
board RAM storage which can be 
accessed in 48 KByte banks— one 
bank for each of four users. Like all 
Altos family members, the 
ACS8000-5 has full asynchronous, 
bisynchronous, and networking 
communications capabilities. 

All Altos systems are packaged 
with the most select features, such 
as the single board Z80A* CPU, 




quality Shugart drives, and optional 
DMA and floating point processors. 
And every Altos system must endure 
extensive reliability testing including 
48 hours of in-process burn-ins. 

Altos supports three industry 
standard operating systems: single/ 
multi-user CP/M,** OASIS} and Altos' 
proprietary AMEX.'" Seven high level 
programming languages are offered 
which are CP/M or AMEX compatible. 

Weed through the micro- 
computer system alternatives. No 
matter what your application, you'll 
pick Altos. 

For specific details about 
pricing or performance, call or write-. 
Altos Computer Systems, 
2360 Bering Drive, San Jose, CA, 
95131, (408) 946-6700, Telex 171562 
ALTOS SNJ. 



1-4 Users 



System 
Software 




Floppy 
Disks: 
.5Mb-2Mb 
And Cartridge 
Tape Back-Up 



Packed with 
Fresh Ideas 

COMPUTER SYSTEMS 



*ZB0A is a registered trademark of Zilog. Inc. 



'CP/M is a registered trademark of Digital Research. Inc. 10ASIS is a registered trademark of Phase One Systems. Inc. © I980 Altos Computer Systems 



Circle 76 on inquiry card. 



BVTE February 1981 



121 



Listing 2 continued: 



WAIT 


SEC 


WAIT2 


PHA 


UAIT3 


SBC #01 




BNE UAIT3 




PLA 




SBC #01 




BNE UAIT2 




RTS 



;bits to be set and update 

(MODEM 

PLA 

ORA MODEMCOPY 

STA MODEMCOPY 

STA MODEM 

PLA (DISCARD MSB OF 
JNEUBITS 



.PROC NEWM0DEMVALUE,1 

A PROCEDURE TO CHANGE THE CONTENTS 
OF LOCATION «0A5 UHICH IS THE (SLOT 
2) LOCATION OF THE MICROMODEM CONTROL 
WORD. THIS IS A ROUTINE WRITTEN ESPE- 
CIALLY FOR USE BY THE LIBRARY UNIT 
MICROMODEM. 

THE ROUTINE LOGOCAL ORS ITS ARGUMENT WITH 
THE CONTENTS OF MODEMCOPY. J067A, SAVES 
THE RESULT IN MODEMCOPY AND WRITES IT TO 
MODEM. *C0A5. 



MODEMCOPY ,EQU 067 A 
MODEM .EQU 0C0A5 

POP PASCAL 



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.BACK TO PASCAL 
PUSH PASCAL 
RTS 



.PROC SNDCHAR 

i APROCEDURE TO OUTPUT ONE CHARACTER 

i THROUGH THE MICROMODEM LOCATED IN 

> SLOT 2. 

i 

r ROUTINE IS CALLED FROM THE LIBRARY 

5 UNIT MICROMODEM. 



RPTR 


.EQU 


0BF18 


WPTR 


.EQU 


0BF19 


CONBUF 


.EQU 


03B1 


BUMP 


.EQU 


0D72C 


DATAOUT 


• EQU 


0778 


OUTA 


.EQU 


0C202 




LDA 


BIOSIN 




JSR 


CONCHECK 




LDX 


RPTR 




CPX 


WPTR 




BEG 


HOME 




JSR 


BUMP 




STX 


RPTR 




LDA 


CONBUF »X 




STA 


DATAOUT 




JSR 


OUTA 


HOME 


LDA 
RTS 


BIOSOUT 



.FUNC GTCHAR 

A ROUTINE TO GET ONE CHARACTER FROM 
THE MICROMODEM DATA INPUT LOCATION 
DATAIN. THE ROUTINE ASSUMES THE RE- 
CEIVER REGISTER IS FULL. 

AFTER FETCHING THE CHARACTER THE ROU- 
TINE OUTPUTS IT TO THE CONSOLE SCREEN 
AND RETURNS THE VALUE TO THE CALLING 
PROGRAM AS A FUNCTION RESULT. 

THIS ROUTINE IS PART OF THE LIBRARY 
UNIT MICROMODEM. 



DATAIN 



.EQU 0COA7 
POP PASCAL 



Listing 2 continued on page 124 



122 February 1981 © BYTE Publications Inc 



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Text continued from page 108: 

status of the acia) 

memory. pntr[0]:=x; (write the 

acia control word) 

This technique is used in the code for 
several of the listed routines. Im- 
plementation of the technique may be 
machine dependent. The alternative 
is to link externally assembled 
machine-language programs to per- 
form the work of BASIC'S PEEK and 
POKE. Such programs are illustrated 
below. 

The procedure "initacia" performs 
initialization of the ACIA by setting it 
up for characters of the length spec- 
ified by the parameter value. It then 
waits for a no-carrier-detected signal 
before returning. 

Several of the procedures call the 
external procedure "newmodem- 
value" which is used to set selected 
bits in the modem control word to 
logical 1 without affecting the status 
of any other bits. By contrast, "set- 
modem" sets all bits (except the sel- 
ected ones) to logical 0. 

Procedure "waitforcarrier" waits a 
period of time to detect a carrier after 
dialing the phone. Unloading the loc- 
ation "datain" in the WHILE... DO 
loop is necessary to satisfy the ACIA, 
as suggested on pages 38 and 39 of the 
owner's manual. 

The procedures "sendchar" and 
"getchar" are Pascal hosts for calling 
the external procedures "sndchar" 
and "gtchar" which are the work- 
horses for simple modem I/O. "Get- 
char" passes the character it gets to 
the calling program via the variable 
parameter "ch" in case the user wishes 
to process "ch" further (say, by send- 
ing it to the system printer). I have 
done this to retain printed copy of 
terminal sessions. 

The statement "setmodem (reset- 
flag);" in the body of the unit will be 
executed as an initialization step 
when the host program is executed. 
Setting the reset flag informs the 
ACIA that default initializations are 
not to be applied when the ACIA is 
first called for input or output. 

The External Procedures 

The assembly-language programs 
called in the implementation block of 
the unit (see listing 2) are part of a file 
called NATIVECODE. I have stored 
these and other low-level utility 
routines, such as the PEEK and POKE 
routines, in a library unit. Therefore 
they can be called from any of my 



Listing 2 continued 


I; 




PLA 


(DISCARD 4 


BYTES OF FUNC- 


FLA 


;tion BIAS 




PLA 






PLA 






LDA 


BIOSIN 




JSR 


CONCHECK 




;get 


' CHARACTER 


AND 


,'PUSH FUNCTION 


RESULT 


LDA 


♦00 




PHA 






LDA 


DATAIN 




PHA 






fOUTPUT TO CONSOLE 


JSR 


VIDOUT 




LDA 


BI0S0UT 




PUSH 


PASCAL 




RTS 







.END 



Listing 3: The Pascal program called "fullduplex". This program makes use of the com- 
piled code of the unit, linked with the assembled code of NATIVECODE. 

PROGRAM full duplex; 

USES Oiicromodeni j 

FUNCTION peeKC Iocs t ion! INTEGER it INTEGER,' EXTERNAL? 

PROCEDURE dialupj 
VAR number ' STRING) 
wordHNTEGER; 



PROCEDURE sSetaeiacntrKVAR 


word 


I INTEGER)! 


BEGIN 








REPEAT 








P33e( output )> 








3oto>;y( r 3 ) » 








wri teln( ' Select 


the ACIA 


control word! ' ) > 


wri telnfwri teln 


1 






wntelnC'CHAR 


PARITY : 


3T0P 


CONTROL-' )» 


writeln< 'LENGTH 


BIT 


BITS 


WORD ' )» 


■ . * , / 






- — ' i : 










uritelnC ' 7 


EVEN 


4- 


r ); 


uritelnC' 7 


ODD 


-1 


5' ); 


uritelnC ' 7 


EVEN 


1 


9' ); 


uritelnC ' 7 


ODD 


1 


13' ),' 


uritelnC' 8 


NONE 





17' j; 


wri telnC ' 8 


NONE 


1 


2i' ); 


uritelnC 8 


EVEN 


1 


25' ;; 


uritelnC' 8 


ODD 


1 


29' ); 


wri teln) 








unteC 'ACIA con 


trol word 


~"*V 


>; 


readlnC word )> 








UNTIL word IN CI 


,5,9,13,1 


7,21,25,29]; 


END) C Setcntrlword 3 







BEGIN C dislup 3 
setroodenK resetf ls£ ); 



Listing 3 continued on page 126 



124 February 1981 © BYTE Publications Inc 




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Pascal programs. As mentioned 
above, when appropriate, POKE and 
PEEK can be substituted whenever 
the variable "memory" is used to ad- 
dress memory. 

When a call-by-value is made to an 
external procedure using scalar 
parameters, the Pascal interpreter 
places the values of the parameters on 
the stack in reverse order of declara- 
tion in the procedure, followed by the 
Pascal return address. External func- 
tions have 4 additional bytes added to 
the stack before the Pascal address. 
When a call-by-variable (or a call-by- 
value using nonscalar parameters) is 
made, a pointer to the variable is 
loaded on the stack. The difference in 
these calls is illustrated in the defini- 
tions of POKE, PEEK, and DIALIT. 

The declarations for NATIVE- 
CODE start with the definitions for 
two macros and several global 
equates; these declarations are 
available to all the routines in the file. 
One macro pops (removes) 2 bytes 
from the stack (this implementation 
of Pascal is 2-bytes-per-word ori- 
ented) and saves them in successive 
locations specified by the parameters 
in the call; the other macro reverses 
this. 

The global equates BIOSIN and 
BIOSOUT establish the addresses of 
two soft switches for gaining access to 
the Apple's BIOS. One reference to 
BIOSIN switches it into program- 
mable memory while two successive 
references enable writing to the BIOS 
section of memory; a reference to 
BIOSOUT switches the BIOS out and 
the Pascal interpreter in. The declara- 
tion for CONCHECK establishes it as 
the starting address in the BIOS for 
the routine that polls the Apple's 
keyboard. VIDOUT is the address of 
the routine for displaying characters 
on the video monitor. 

The procedure DIALIT illustrates 
call-by-value with a nonscalar value: 
a pointer to the number to be dialed is 
passed to the program. After storing 
the pointer, the routine prepares to 
dial by setting the temporary loca- 
tions HANGUP and PICKUP and 
finding the length of the number. 
Dialing is accomplished by alter- 
nating the phone between the onhook 
and offhook states. (We assume the 
phone is off the hook when the 
routine is called.) The recommended 
dialing protocol is 61 ms onhook 
followed by 39 ms offhook with an 
interdigit delay of at least 600 ms. 

The procedure SNDCHAR is used 



Listing 3 continued: 

P32e( output )i 

2oto;;y( 0»5 )» 

writeln 1 ; 'Enter the Fhone number.'); 

writeln i 

write* ' — > ' )r 

re3dln'! number )r 

2et3ci3cntrl( word )i 

P32e( output )»' 

2oto>;yi Of 5 )■ 

writei ' Preparing to di3l» pie3se wait...' )r 

init3cis( word )? 

picKupJ 

setniode( originate »hiah ) > 

writeln( 'OK' )i 

disl( number )i 

writeln > 

writeln( 'U3itir,a for carrier. .»' )> 

w3itforc3rrier» 

end; 

PROCEDURE terminal? 
VAR chrCHARi 

error {INTEGER; 

1 
BEGIN 
p3Se(output )i 
2oto>;y(0i5)i' 

writelnt 'C3rrier OK. Begin coBaunic3tions.' )> 
en3bletr3nsnii t j 
REPEAT 
IF sci3error 
THEN IF NOT C3rrier 
THEN BEGIN 

unitcle3r( 1 )> 
exit( terminal )i 
END 
ELSE BEGIN 

write( '*' )i 
error i=peek( d3t3in )i 
END 
ELSE IF rcvrfull 

THEN 2etch3r(ch) 
ELSE sendch3r; 
UNTIL NOT C3rrierr 

end; 

FUNCTION tryssSsmtBOOLEAN; 
YAR snswrtCHARi 
BEGIN 
REPEAT 

P32e( output ); 

2oto>:y(0>5)i' 

write('No C3rrier. Try 333in? (Y/N )->')> 

re3d( 3nswr )! 

writeln? 

try323inl=3nswr IN C'Y'r'y']; 
UNTIL 3nswr IN L'V ,'N' , 'y'.'n' li 

end; 

BEGIN C fullduple;-: 3 
REPEAT 
di3lup; 
IF C3rrier 
THEN termin3i; 
UNTIL NOT try3=J3in; 
h3naup; 
END. 



126 February 1981 © BYTE Publications Inc 



Circle 79 on inquiry card. 



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to transmit characters through the 
modem. It does not check to see if the 
ACIA transmitter register is empty; 
this should be done in the calling pro- 
gram using "transempty". Location 
CONBUF is the start address for the 
BIOS's console keyboard buffer, and 
WPTR and RPTR indicate the num- 
ber of characters written to and read 
from the buffer. BUMP is the address 
of a routine that updates these 
numbers. 

SNDCHAR first polls the console 
keyboard. If there is a character in the 
buffer, it loads it into DATAOUT, 
then calls the output routine on the 
modem. At the end of all this, the ad- 
dress for returning to Pascal is still on 
the top of the stack, so an RTS (re- 
turn from subroutine) instruction 
transfers control to the calling pro- 
gram. 

In GTCHAR, VIDOUT is the ad- 
dress of the BIOS routine for sending 
characters to the video monitor. 
GTCHAR (analogous to SNDCHAR) 
assumes the ACIA's receiver register 
is full, a condition that should be 
checked in the calling program. The 
routine starts by saving the Pascal 
return address, discarding 4 bytes of 
stack bias, and polling the Apple's 
keyboard. It then fetches the charac- 
ter from the input location DATAIN, 
pushes it on the stack as the function 
result, and jumps to VIDOUT to 
display the character. 

Using the Unit 

At this point, we need only compile 
the unit, assemble the file NATIVE- 
CODE, link the two, and store the 
resulting final code in a library in 
order to use the unit. The program 
"fullduplex" (see listing 3) illustrates 
the use of the unit. The program also 
makes a call to the external function 
PEEK. 

The main body of "fullduplex" and 
the procedure "dialup" are self- 
documenting. As for "terminal", the 
procedure continues sending and re- 
ceiving characters until an ACIA er- 
ror is found. If the error is the lack of 
a carrier, the program hangs up the 



phone, clears the keyboard buffer of 
any junk, and exits "terminal" to 
"tryagain". If any other error is en- 
countered, the character "§" is writ- 
ten to the video display and the re- 
ceiver register is emptied to clear the 
error condition. I have used this pro- 
gram to communicate with several 
time-sharing systems and it has no 
problem keeping up at 300 bps. 

Modifying the Apple's BIOS 

The procedures presented thus far 
are quite adequate for a variety of 
dumb terminal applications, but they 
are not particularly well suited to 
mass-data transfer applications such 
as transmitting preprocessed files or 
whole volumes. For the latter, we 
would like to make use of the reper- 
toire of UCSD Pascal intrinsic pro- 
cedures for processing files. The key 
to using these procedures is an 
understanding of the BIOS (basic in- 
put/output system). 

Each implementaton of UCSD 
Pascal, such as Apple's, requires an 
interpreter and a BIOS to support it. 
Roughly speaking, the interpreter 
translates p-code (the code emitted by 
the Pascal compiler) into machine 
language, and the BIOS handles the 
physical I/O to system devices. The 
BIOS modifications discussed below 
apply only to the Apple and may re- 
quire revision if new versions of the 
BIOS are released. Hints on modify- 
ing another system's BIOS may 
perhaps be found in the UCSD Pascal 
User's Manual published by SofTech 
Microsystems. However, it is likely 
you will need a commented listing of 
your BIOS; I obtained a copy of the 
Apple BIOS from Apple in the form 
"The Preliminary Guide to Inter- 
facing Foreign Hardware." 

To fully explain the operation of 
the BIOS and the options the pro- 
grammer has for modifying it would 
require a great deal of discussion. In- 
stead I will provide a summary of its 
operation and offer a set of modifica- 
tions that have worked for me. 

Whenever a call for input or output 
is made from a Pascal program, the 
interpreter formats the data and 
determines which device is being 
called. Following this, the BIOS is 
switched in and then determines how 
the device is interfaced with the 
system. As currently configured, the 
Apple's interpreter and BIOS can 
recognize four types of external 

Text continued on page 136 



128 February 1981 © BYTE Publications Inc 



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COUNTRY 




TELEPHONE 



Listing 4: External procedure that modifies Apple BIOS for use 
with the Micromodem II. This expands the Apple's utility 
beyond that of a dumb terminal, allowing mass transfer (and 
processing) of whole files via the Micromodem II. 



.PR0C SYSGEN 



BIOSIN 


.EQU 0C083 


BI0S0UT 


.EQU 0C08B 


C0NCHECK 


.EQU 0D681 


ACIA 


.EQU 0C0A6 


DATAOUT 


.EQU 0778 


DATAIN 


.EQU 0C0A7 


M0DEH 


•EQU 0C0A5 


0UTA 


.EQU 0C202 


IC0M 


.EQU 0D7A3 


RINIT 


•EQU 0D79C 


RWRITE 


.EQU 0D80? 


UC0H 


.EQU 0D81F 


RC0M 


.EQU 0D85D 


RREAD 


.EQU 0D84E 




LDA BIOSIN 




LDA BIOSIN 




LDY #00 


XRINIT 


LDA PRG2,Y 




STA RINITfY 




INY 




CPY #03 




BCC XRINIT 




LDY #00 


XlCOtt 


LDA PRG3,Y 




STA ICOhSY 




INY 




CPY #0A 




BCC XIC0M 




LDY #00 


XRWRITE 


LDA PRG4,Y 




STA RURITErY 




INY 




CPY #06 




BCC XRWRITE 




LDY #00 


XUCOM 


LDA PRG5,Y 




STA WCOMfY 




INY 




CPY #11 




BCC XWC0M 




LDY #00 


XRREAD 


LDA PRG6,Y 




STA RREAD »Y 




INY 




CPY #03 




BCC XRREAD 



130 February 1961 © BYTE Publications Inc 



Listing 4 continued on page 132 
Circle 82 on Inquiry card. > 




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PASCAL/MT- Is a trademark of MT Micro Systems 



Listing 


4 continued: 
LDY #00 






XRCOH 


LDA PRG7,Y 
STA RCOMfY 
INY 

CPY *0F 
BCC XRCOM 

LDA BIOSOUT • 
RTS 






PRG2 


•BYTE 4Cf0A3f0D7 


JJMP 


ICOM 


PRG3 


.BYTE 0A9f03 


jlda 


♦03 




• BYTE 8DfOA6fOC0 


J STA 


ACIA 




•BYTE 0A9f 15 


JLDA 


♦ 15 




.BYTE 8Df0A6f0C0 


JSTA 


ACIA 


PRG4 


.BYTE 0A8 


JTAY 






•BYTE 0A2f00 


JLDX 


♦00 




.BYTE 4CflFfOD8 


JJMP 


WCOM 



rRG; 



•BYTE 20f81»0D6 JJSR CONCHECK 
.BYTE OADfOA6fOC0JLDA ACIA 
.BYTE 29f02 
•BYTE 0F0f0F6 
.BYTE 8Cf78f07 



.BYTE 20f02»0C2 
.BYTE 60 



JAND #02 

JBEQ WCOM 

JSTY DATAOUT 

JJSR OUTA 
JRTS 



PRG6 
PRG7 



.BYTE 4C»5DfOD8 JJMP RCOM 

.BYTE 20f81f0D6 JJSR CONCHECK 
.BYTE OADfOA6fOC0JLDA ACIA 
.BYTE 4A JLSR A 
.BYTE 90,0F7 JBCC RCOM 
.BYTE OADfOA7,OC0JLDA DATAIN 
.BYTE 0A2»00 JLDX ♦OO 
.BYTE 60 JRTS 



.END 

PROGRAM startupJ 

PROCEDURE sysSenJEXTERNALJ 

BEGIN 
suss^en J 

3oto>;y(0f5)J 

writeln* 'Welcoee to Dr. Wo's Apple Pascal!' )J 
writelnJ 

writeln('The satem has Just been modified to' )J 
writeln< ' enable communications through the' )f 
writeln( 'Hicrotodem II in slot 2.')J 
writelnJ 

writeln( 'Please set the DATE usins 1 the Filer.' )J 
END. 

Listing 5: A program to test the Micromodem II system. The program prompts the 
operator, then puts the modem through its various modes of operation. 

PROGRAM tesUodem! 

(This program tests the transmission and reception of the printing 
characters through the Micromodem II installed in slot 2 on the 
Apple's board. The program uses the Library Unit '»icromodem' and 
custom 1/0 drivers installed as modifications in the Apple's BIOS.} 

Listing 5 continued on page 134 



132 February 1981 © BYTE Publications Inc 



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If automatic and accurate date and time entry three months). Timing is provided by a crystal 
is important to your system on power-up — controlled oscillator. Prices are U.S. domestic 
you need a Digital Pathways battery sup- single piece. Quantity discounts available. 
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Circle 84 on inquiry card. . byte February i98i 133 



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Listing 5 continued: 

USES roicroniodeniT 

CONST lowch3r= ' ' i C blank 3 
hi5hch,3r = 'z' J 

VAR choutrchin.CHAR; 
error count! INTEGER? 
«! ARRAYl mode] OF STRINGC10], 
bJARRAYCbsudrste] OF STRINGC103J 
remin»remout! INTERACTIVE, 

BEGIN C main 3 

reset( reminr renin !' )> 
rewrite( remout.'remout!' )> 

m[ answer ]!=' answer' J 
ni[ori5in3te]! = 'oris : in3te' 5 
b[low]! = '110 baud', 
b[hiah]! = '300 baud' i 

FOR nid! = 3nswer TO originate DO 
FOR br.=low TO hish DO 
BEGIN 
FBSeC output )> 
5oto>;a(0»5), 

writeln( ' Testing ' rraCnid]?' mode> '»b[br])» 
writelnJwriteln? 

writeln( ' Resetting modem and ACIA.')» 
write( 'Please wait...' )> 
setmodemf self test-fr-esetf 135 )> 
initsci3(21 )i 
picKupj 

setmode(mdfbr )5 
writelnCOK' )i 
writeln? 

write( 'Please wait for carrier...'); 
enabletransait J 
waitforcarrier J 
writelnC'OK' )> 

writeln? 

writeln( ' Beeir; test*..')? 
errorcount!=OJ 

FOR chout!=lowchsr TO hishchar DO 
BEGIN 

write( remoutfchout )> 

resdf remin»chin )> 

IF (ord(chout )-ord( lowchar ) ) HOD 40<39 
THEN write(chout) 
ELSE writeln( chou t )J 

IF choutOchin 
THEN BEGIN 

errorcount.=errorcount+l 5 

writelnC 'Error in sending '»chout)i 

end; 
end; 

writelnJwriteln; 

writeln( ' Total errors this test= ' »errorcount )» 

writelnj 

write('T«pe <ret> to continue. ..' )>readln; 

end; 



134 February 1981 © BYTE Publications Inc 



Circle 86 on inquiry card. 



Circle 87 on inquiry card. 



i^c 



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POLISHES APPLE 







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Basic or 8 sector Pascal comes 
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The Model A-40 actualy costs 
a lot less than Apple Disk II drives. 
Yet it provides 40 tracks instead of 




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Apple and Apple II are registered trademarks of APPLE COMPUTERS INC., SAN JOSE, CALIFORNIA 



714/997-9260 



Text continued from page 128: 

physical devices — consoles, printers, 
disks, and remote input/output 
devices (such as modems) — provided 
these devices are interfaced via an 
Apple-brand card. For nondisk I/O, 
the Apple's BIOS recognizes the Ap- 
ple communications, serial, and 
parallel-printer cards. If a foreign 
card is plugged into a slot, the Apple 
will know that something is there, but 
will not know how to communicate 
with it unless the card's setup happens 
to coincide with one of the Apple 
cards. Such is the case for the 
Micromodem interface: the Apple 
thinks it is communicating with a 
remote device via an Apple com- 
munications card, but it can't do I/O 
because of an address mismatch. The 
solution is to insert the correct ad- 
dresses. 

The Apple's BIOS is set up to do 
three things with the modem: init- 
ialize it, read from it, and write to it. 
In each case, the BIOS receives con- 
trol from the interpreter, jumps to a 
location reserved for the appropriate 
operation with the remote I/O de- 
vice, determines which type of card it 
is dealing with, then jumps to a loca- 
tion reserved for that combination of 



card and operation. After completing 
I/O, it returns control to the inter- 
preter. This combination of jumps 
was observed in my modifications. 
Since I have no Apple communica- 
tions cards connected to my system, I 
customized the locations to suit the 
requirements of the Micromodem. 
These modifications are applied at 
system startup time via an external 
procedure SYSGEN hosted by the 
program "startup". 

The procedure SYSGEN (see listing 
4) first enables writing the BIOS. 
Then it modifies the routine located 
at RINIT so that a JMP to location 
ICOM is made. In the unmodified 
BIOS, RINIT is the name of a routine 
for initializing the remote device: it 
first determines what type of card is 
in slot 2; after finding a communica- 
tions card it jumps to ICOM to in- 
itialize the card. Under these modifi- 
cations, control is transferred to 
ICOM immediately. SYSGEN next 
modifies RWRITE, the "write-to-re- 
mote" routine, and WCOM, the 
"write-to-comm-card" routine. Simi- 
lar to the unmodified initialization 
routines, the interpreter passes con- 
trol to RWRITE, which determines 
the type of card occupying slot 2. 




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Upon finding a communications card, 
it transfers control to WCOM. 
SYSGEN closes with modifications to 
RREAD and RCOM. 

One can implement the modifica- 
tions, as I have, in a program that is 
executed each time the system is 
booted up. First assemble SYSGEN, 
then link it to a Pascal host "startup", 
and then store the final code in the file 
SYSTEM. STARTUP on the boot 
disk. The program will be executed 
automatically at boot time. 

A Test Program 

The program "testmodem" tests the 
modem and the BIOS modifications. 
It starts by opening the files "remin" 
and "remout" and associating them 
with the volumes "remin:" and 
"remout:" respectively. The latter are 
the names given to remote I/O de- 
vices under Apple UCSD Pascal. 
Following this procedure, the pro- 
gram sets up some strings to prompt 
the operator, and the nested 
FOR... DO loops put the modem 
through its various operating modes. 

When the statement "write 
(remout, chout);" is encountered, the 
interpreter determines that a call for 
output to slot 2 is being made. At this 
time control is transferred to the 
BIOS location RWRITE. In order for 
execution to proceed satisfactorily 
from there, the system must recognize 
the card in slot 2. The situation is 
similar for the statement "read 
(remin, chin);". Thus, the program 
serves as a test of the BIOS modifica- 
tions as well as the modem. 

Summary 

The library unit "micromodem" 
and the BIOS modifications presented 
here are a complete package of 
building blocks for developing 
remote communications programs us- 
ing the Micromodem running under 
the Apple implementation of UCSD 
Pascal. Techniques similar to those 
described here should enable 
operators of other systems to enjoy 
the same advantages. ■ 



References 

1. Grogono, P. Programming in Pascal. 
Addison-Wesley, 1978. 

2. Hyde, D J. Micromodem II Owner's 
Manual, 2nd edition. Norcross GA: Hayes 
Microcomputer Products Inc, May 1979. 

3. "The Preliminary Apple Pascal Guide to 
Interfacing Foreign Hardware." Cupertino 
CA: Apple Computer Co, Dec 1979. 

4. UCSD Pascal User's Manual. San Diego 
CA: SofTech Microsystems, 1978. 



136 February 1981 © BYTE Publications Inc 



Circle 88 on inquiry card. 



Circle 89 on inquiry card. 




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Puts muscle in your 

TRS-80* 



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Technical Forum 



Recording with Current 
Instead of Voltage 



David Hein 
2821 Chariot Lane 
Garland TX 75042 

Most of the articles I have seen on the theory of mass 
storage using cassettes begin with a discussion of how the 
magnetization of the tape depends on current flow, and 
how changing the head-drive current creates cells of dif- 
ferent magnetization. During a read, it is normally as- 
sumed that the sharper the transitions between current 
and lack of current, the higher the output and the greater 
the density (or speed) that can be used. 

Yet after all this discussion on current, head drive is 
most often performed by a voltage amplifier driven to 
saturation. Current devices should be driven with current 
rather than voltage. 

The circuit I use for this is simple. It consists of two 
current drivers, some control gates for writing, an RS 
flip-flop for reading, and an amplifier with a gain of 200, 
capacitively coupled to a differential sense amplifier (see 
figure 1 on page 140). 

Four channels along with voltage amplifiers easily fit 
on a two-sided, 4- by 6-inch card with standard 22-pin 
connectors (see photo 1). That's enough circuitry for two 
tracks each on twin transports. 

My tape deck, which has digital (narrow-gap) heads is 
capable of 8 K bps (bits per second) at 5 ips (inches per 
second). My neighbor's standard cassette deck is capable 
of 2400 bps at 1% ips. ■ 




Photo 1: Finished version of the circuit shown in figure 1. This 
4- by 6-inch board with 22-pin connector has enough room for 
the circuitry of two tracks each on dual recorders. 



138 February 1981 © BYTE Publications Inc 



Circle 91 on inquiry card. 



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Systems, inc. 

Market Square, Box 248 
Lafayette, Indiana 47902 
317-448-1616 

Dealer/distributor/OEM inquiries invited. 



YES, please send me more information on the 
remarkably flexible MDBS Data Base System. 




Name 



(Please print) 



Title 



Company 
Address _ 
City 



(State) 



(Zip) 



Phone 



MAIL TO: Micro Data Base Systems, Inc. 
Dept. B 
P. O. Box 248 
Lafayette, IN 47902 



Circle 92 on Inquiry card. 



BYTE February 1981 139 




lA m 



ia |6 



Figure 1: /4 circuit for driving record heads with current rather than voltage. This simple circuit enables data transfer rates of up to 
2400 bps (bits per second) on a standard cassette tape recorder. 



140 February 1981 © BYTE Publications Inc 




anew 






is Dor n! 











a better computer system 
any way you look at it. 



The facts speak for themselves. The QUAY 500 SERIES 
offers more for the money than North Star Horizon® 
computers. 

MORE TECHNICAL FEATURES. A single board computer in- 
stead of a backplane with multiple boards, means fewer parts, 
fewer interconnections and fewer problems □ additional disk 
capacity for more program storage □ DMA controlled disk 
transfers for increased system performance o on-board expan- 
sion capabilities for additional parallel and serial ports, and 
EPROM □ AC convenience outlets □ a more compact design. 
IMMEDIATE DELIVERY. The 500 SERIES is available off the 
shelf for virtually immediate delivery. No waiting for far off de- 
livery dates for this one. 

LOWER PRICE. The advanced technology engineered into 
Quay computers actually lowers our cost to manufacture. 
The price of the 500 SERIES is about 20% lower than the 

Horizon-2-32K-D — and 
our 520 SERIES also offers 
significant savings over the 
Horizon-2-32K-Q. 
The bottom line is simple. 
There is a new star in the 
computer field. The 500 
SERIES by Quay. It out- 
shines all of the competi- 
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COMPARE FOR YOURSELF: 




SPECIFICATION 


QUAY 500 


HORIZON-2-32K-D 


Architecture 


Single Board 


S100 bus 


CPU 


Z80A, 4MHz. 


Same 


Dynamic RAM(std) 


64Kb. 


32Kb. 


Disk drive type 


Doubledensity 


Same 


No. of drives (std/max) 


2/4 


Same 


Capacity per drive (on-line) 


200 Kb. 


180 Kb. 


Direct Memory Access (DMA) 


Yes 


No 


CP/M® disk operating system 


Standard 


Optional 


Unit Price 


$2,995. 


$3,095. 



Advanced single board modular design. 



SPECIFICATIONS 


QUAY 520 


HORIZON-2-32K-Q 


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Unit Price 


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$3,595. 



The QUAY 500 offers technical superiority — availability — a $2,500 price! 



CP/M ^ is a registered trademark ol Digital Research 

Horizon is a registered trademark ol North Star Computers, Inc. 

ouAa 



CORPORATION 

P.O. Box 386, Freehold, New Jersey 07728 ■ (201) 681-8700 
Factory: Route 34, Wall Township, New Jersey 07719 

DISTRIBUTOR AND REPRESENTATIVE INQUIRIES WELCOME 



Circle 93 on inquiry card. 



BYTE February 1981 141 



Dynamic Memory: 
Making an Intelligent Decision 



Larry Malakoff 

Measurement Systems and Controls 

867 N Main St 

Orange CA 92668 



Mention the words dynamic 
memory to an S-100 bus user and the 
responses will vary from one end of 
the spectrum to the other. In the early 
days of the S-100 bus, many users 
had bad experiences with poorly 
designed dynamic-memory boards. 
The problems varied from inadequate 
memory refreshing to designs that 
worked with only a particular pro- 
cessor board. However, things have 
come a long way since then. For the 
vast majority of today's applications, 
dynamic memory offers the best 
cost/performance ratio available. 
With so many of the large S-100 com- 
puter manufacturers such as 
Cromemco, North Star, Vector 
Graphic, and others using dynamic 
memory in their systems, all users 
should seriously consider the advan- 
tages of including dynamic memory 
in their next system design. 

Dynamic vs Static 

In the S-100 world, static memory 
is the alternative to dynamic 
memory. When comparing the two 
types, three major advantages of 
dynamic memory are apparent. First, 
dynamic boards contain more 
memory than static boards. Even 
with the supporting control logic that 
dynamic memory requires, today's 
largest available S-100 memory- 
board sizes are 64 K bytes for 



About the Author 

Larry Malakoff is the Marketing Director of 
Measurement Systems and Controls Inc, 
located in Orange, California. He has been in- 
volved in the design of 5-100 dynamic-memory 
boards and is currently working with 
customers to solve their application re- 
quirements for system memory. Larry received 
his Master of Science in Engineering from 
UCLA and has been involved in electronic 
design for over eight years. 



dynamic memory and 32 K bytes for 
static memory. For those systems that 
require large amounts of memory, 
such as the Cromemco and Alpha 
Micro multi-user systems, the in- 
creased density of dynamic memory 
can mean the difference between hav- 
ing enough available slots on the 
motherboard for all the cards 
necessary to complete the system or 
not being able to fit all of the required 
cards into a given chassis. 

The second and probably most im- 
portant advantage of dynamic 
memory is the low level of power 
dissipated. This not only reduces the 
amount of heat generated, but also 
reduces the current requirements 
from the power supply. A typical 
64 K-byte dynamic-memory board 
dissipates approximately 8 watts of 
total power compared to as much as 
50 watts for 64 K bytes of static 
memory. This decrease in power 
dissipation of more than sixfold can 
make a big difference in the reliability 
of the entire system. This is especially 
true when the system contains more 
than 64 K bytes of memory, as in a 
multi-user application. Since the 
reliability factor for electronic equip- 
ment decreases exponentially as the 
operating temperature increases, the 
mean time between failures can be 
drastically improved by using 
dynamic memories in the larger 
memory-intensive systems. 

The third major advantage of 
dynamic memory is cost. Historical- 
ly, its cost has always been lower, 
and this will continue to be so due to 
the increased density of dynamic- 
memory circuits. Once an integrated- 
circuit manufacturer has regained the 
initial development investment 
(assuming the yields are about equal), 
the price for higher-density dynamic- 
memory circuits can be about the 



same as for lower-density static- 
memory devices. Since it takes sixty- 
four of the 4 K-by-1-bit static- 
memory devices to build a 32 K-byte 
memory board as compared to thirty- 
two of the 16 K-by-1-bit dynamic- 
memory circuits to build a 64 K-byte 
dynamic-memory board, it becomes 
apparent, even when the control logic 
is taken into account, that a dynamic- 
memory board costs less to build than 
the corresponding static-memory 
board. 

In comparing the two types of 
memory, there is one application 
where static memory may be a better 
choice. Not all types of DMA (direct 
memory access) controllers will cor- 
rectly interface with all types of 
dynamic-memory boards. Depending 
on the particular DMA controller, 
static memory may be the only type 
that will work correctly. More will be 
said about this later. 

Memory Features to Look For 

Now that the general merits of 
dynamic-memory boards have been 
brought to light, it is important to 
discuss some of the differences be- 
tween the commercially available 
designs, and what features in par- 
ticular to look for when choosing a 
dynamic-memory board for your 
system. This discussion will be 
separated into two application areas 
— those requiring a maximum of 
64 K bytes of memory and those re- 
quiring more than 64 K bytes of 
memory (for multi-user and 
multitasking applications incor- 
porating software-controlled, bank- 
selectable memory). 

Many manufacturers make only 
one memory-board product that tries 
to bridge the gap between the two 
types of applications. However, these 
two applications require that the 



142 February 1981 © BYTE Publications Inc 



r hen you pick a Daisy. 
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The Vista V300 is exactly that, a "peach" of a daisy wheel printer both from the standpoint of price 
and performance. 

Think of it, a printer at nearly half the price (when compared to models even remotely competitive in 
quality) combined with the ultimate in reliability, print quality, and flexibility. 

Typical Comments: "Superb print quality!", "Highly reliable.", "Definitely letter quality. . . I can't 
believe the price tag.", "Best use I've seen yet of LSI Technology." 

But judge for yourself — look at the V300 features and keep in mind this is a letter quality printer at 
dot matrix prices. 

• Tractor option available 

• Print Speed — 25 CPS (Optional 45 CPS for $2,195) 

• Print Wheel — Industry standard 96-character Daisy Wheel 
(including the extended-life dual plastic wheels) 

• Service — Prompt maintenance/service agreements avail- 
able nationwide 

• Interface — Industry standard parallel (RS232-C optional) 

• Printable Columns — 136 

• Warranty — 90 days parts and labor, one year parts only 

• Proportional, bi-directional printing • Programmable VFU 

• Extensive self-test functions • Hardware and software 
compatible 

Vista does it again! Quality, Price and Perfor- 
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V200E20 Disc Drive 

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Monitor 



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Can also be used for 

Data Processing 



The Vista Computer Company 1401 Borchard Street* Santa Ana, California 92705" 

™CPM Is a trademark of Digital Research 



714/953-0523 



Circle 94 on inquiry card. 



BYTE February 1981 143 



memory used have different features, 
often resulting in a compromise 
where one or both of the application 
areas lacks the necessary hardware 
for a truly cost-effective solution. 

Single-User Features 

In a single-user system that requires 
64 K bytes or less of memory, the 
most important feature to have is the 
ability to deselect memory in as small 
an increment as possible. For the ma- 
jority of 64 K-byte dynamic-memory 
boards that offer this feature, 4 K 
bytes is usually the smallest block of 
memory that can be turned off. 

la 



(Some of the older 16 K-byte 
memory boards allow deselection to 
1 K bytes.) This feature is necessary 
to allow the system monitor in read- 
only memory and memory-mapped 
controller cards to reside in the 
memory-address space without in- 
terfering with normal memory opera- 
tions. 

Another useful feature is the ability 
to buy a memory board in either a 16, 
32, 48, or 64 K-byte size, with those 
boards containing less than 64 K 
bytes able to be expanded to 64 K 
bytes by inserting the necessary in- 
tegrated circuits into empty sockets. 




Photo 1: Different kinds of memory boards. These two 64 K-byte memory boards have 
fundamental differences that tailor them for specific types of systems. The Measurement 
Systems and Controls DMB6400 (photo la) is intended for multi-user and multitasking 
systems and provides a bank-select feature so that memory addresses may be shared by 
users. The DM6400 (photo lb) is produced specifically for single-user systems and has a 
deselect feature that allows memory-mapped peripherals to occupy any 4 K address 
block. Both boards are manufactured by Measurement Systems and Controls of 
Orange, California. Prices are $1195 and $895 respectively. 



This gives the small user the ability to 
expand as necessary. It is important 
that the manufacturer test these 
boards as full 64 K-byte boards even 
though they may be sold as 
16 K-byte boards. This is the only 
way the end user can be assured that 
the board will work when the extra 
devices are plugged in to increase the 
memory size. 

Multi-User Features 

Most multi-user and multitasking 
S-100 systems require bank-selectable 
memory boards. The requirements 
placed on the memory board for these 
applications are quite different from 
those placed on the single-user ap- 
plications. A typical multi-user 
system might have an operating 
system of 48 K bytes and five user 
banks of 16 K bytes each. The 
operating system might occupy the 
upper 48 K-byte address space and 
be on all the time, while the five users 
might share the lower 16 K-byte ad- 
dress space. Only one user can be on 
at a time (there can never be more 
than 64 K bytes of memory on at any 
one time), but the operating system 
allows all five users to access the com- 
puter on a rotating timeshared basis. 
Through software control, each of 
the 16 K-byte banks of memory is 
turned on or off as required. This is 
usually accomplished by doing an 
OUT instruction to a particular I/O 
(input/output) port that the memory 
board is set to decode. The data on 
the bus then determines which banks 
are to be on or off. 

A 64 K-byte dynamic-memory 
board optimized for this type of ap- 
plication would allow the user to im- 
plement the above example with only 
two memory boards. Other 
64 K-byte dynamic-memory boards 
that compromise on the hardware 
design would require one 48 K-byte 
memory board and five 16 K-byte 
memory boards. In this case, the 
number of motherboard slots re- 
quired increases, the total power 
dissipation increases, and the total 
cost of memory increases. 

The difference between the two 
memory boards in the above example 
is in how the 64 K bytes of memory 
are partitioned into software- 
selectable banks. The optimal design, 
considering the limitations of board 
"real estate," is to have four totally 
independent 16 K-byte banks of 
memory. This allows the user to have 



144 February 1981 © BYTE Publications Inc 



Circle 95 on inquiry card. 



Multi-User 



UniFLEX is the first full capability multi-user 
operating system available for microprocessors. 
Designed for the 6809 and 68000, it offers its 
users a very friendly computing environment. 
After a user 'logs-in' with his user name and 
password, any of the system programs may be 
run at will. One user may run the text editor 
while another runs BASIC and still another runs 
the C compiler. Each user operates in his own 
system environment, unaware of other user 
activity. The total number of users is only 
restricted by the resources and efficiency of the 
hardware in use. 



The design of UniFLEX, with its hierarchical file 
system and device independent I/O, allows the 
creation of a variety of complex support 
programs. There is currently a wide variety of 
software available and under development. 
Included in this list is a Text Processing System 
for word processing functions, BASIC interpreter 
and precompiler for general programming and 
educational use, native C and Pascal 
compilers for more advanced programming, 
sort/merge for business applications, and a 
variety of debug packages. The standard 
system includes a text editor, assembler, and 
about forty utility programs. UniFLEX for 6809 is 
sold with a single CPU license and one years 
maintenance for $450.00. Additional yearly 
maintenance is available for $100.00. OEM 
licenses are also available. 



FLEX 



TM 



Multi-Tasking 

UniFLEX is a true multi-tasking operating system. 
Not only may several users run different 
programs, but one user may run several 
programs at a time. For example, a 
compilation of one file could be initiated while 
simultaneously making changes to another file 
using the text editor. New tasks are generated 
in the system by the 'fork 1 operation. Tasks may 
be run in the background or 'locked' in main 
memory to assist critical response times. Inter- 
task communication is also supported through 
the 'pipe' mechanism. 



UniFLEX is offered for the advanced 
microprocessor systems. FLEX, the industry 
standard for 6800 and 6809 systems, is offered 
for smaller, single user systems. A full line of FLEX 
support software and OEM licenses are also 
available. 



Box 2570, West Lafayette, IN 47906 
(317) 463-2502 Telex 276143 

'"UniFLEX and FLEX are trademarks of Technical 
Systems Consultants, Inc. 



bank sizes that are any multiple of 
16 K, such as four 16 K-byte banks 
or two 32 K-byte banks or one 
16 K-byte bank and one 48 K-byte 
bank, etc, all of which are software 
selectable. In addition, the four banks 
should be independently addressable 
on the four 16 K boundaries: hexa- 
decimal 0000, 4000, 8000, and C000. 
A much more simplistic approach is 
to bank-select the entire memory 
board, the bank size then being deter- 
mined by the size of the memory on 
the board. 

Other important features that a 
bank-selectable memory board 



should have include the ability to 
decode any of the possible 256 I/O 
port addresses and have up to eight 
banks of memory for each port ad- 
dress. In addition, the user should be 
able to turn on or off any of the 
switchable banks when a system reset 
occurs. One last feature, which can 
be very valuable when troubleshoot- 
ing a system with more than one 
64 K-byte bank-selectable memory 
board, is an LED (light-emitting 
diode) indicator for each bank of 
memory that is being accessed. The 
flashing pattern of the LEDs can in- 
dicate where a problem is. 



Waiting On Delivery 
of ADECLA120? 



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baud operation with a DS120 Terminal Controller. 

The Datasouth DS120 gives your DECwriter® II the high speed 
printing and versatile performance features of the DECwriter® III 
at only a fraction of the cost. The DS120 is a plug compatible 
replacement for your LA36 logic board which can be installed in 
minutes. Standard features include: 

•RS232 interface 



• 165 cps bidirectional printing 
•Horizontal & Vertical Tabs 
•Page Length Selection 
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•1000 character print buffer 
•X-on, X-off protocol 
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from the Fortune 500 to personal computing enthusiasts. In 
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upgraded to take advantage of to- 
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and strict quality control 
ensure dependable per- 
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Best of all, we can deliver 
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DATASOUTH COMPUTER CORPORATION 

4740 Dwight Evans Road • Charlotte, North Carolina 2S210 • 704(5236500 




jjgUiffij^M^Q 1 



One last word on bank-selectable 
memory is that a well-designed board 
will allow the user to work correctly 
with the slightly different approaches 
taken by the main manufacturers of 
multi-user systems: Alpha Micro, 
Cromemco, North Star, and Digital 
Research. (Digital Research only sup- 
plies the multi-user operating system, 
MP/M.) 

Common Features 

There are several other important 
features that are common to both 
single-user- and multi-user-optimized 
memory boards that the system 
designer should look for. The most 
important feature is the ability of the 
memory board to work with as many 
different processor boards as possi- 
ble. This includes the standard 
8080A-, Z80A-, and 8085-based 
boards, as well as the more advanced 
16-bit machines (such as Alpha Micro 
and Marinchip's M9900). 

This would not seem to be a major 
problem since all products manufac- 
tured for the S-100 bus should work 
with one another. However, in the 
real world this is not always the case. 
The S-100 bus started with and was 
defined around the 8080 microproces- 
sor. As other microprocessors made 
their way onto the S-100 bus, they 
had to emulate the timing of the 8080. 
Each company came up with its own 
version for this timing. As a result, it 
is difficult to find two Z80A boards 
that generate their S-100 signals alike. 

This creates a challenge to the 
dynamic-memory board manufac- 
turers to come up with a flexible 
internal-timing scheme that allows 
the memory-timing circuits to adjust 
to the differences in the processor 
boards. The best way to achieve this 
is to use a minimum number of the 
S-100 bus-timing signals and, if at all 
possible, to avoid the use of the 
pSYNC signal. This one signal has 
created more problems than any 
other due to the many different 
processor-board designs manufac- 
turers have come up with. The best 
designed dynamic-memory boards 
will correctly interface with the vast 
majority of the different board types 
available today, but no single 
dynamic-memory board can claim to 
work with them all. 

Most of today's dynamic-memory 
boards use transparent (or invisible) 
refresh. A window in the processor 
timing is found where the memory 



146 February 1981 © BYTE Publications Inc 



Circle 96 on inquiry card. 



MICROBYTE INTRODUCES 

PROFIT FOR YOUR BOTTOM LINE 




4 PORT I/O 

•Quad RS-232C Serial Ports, One 20mA Current Loop Port 

• Fully IEEE S-100 Bus Compatible 

•Asynchronous Communications with Z80A-Dart(TM) or 

Synchronous Communications with Z80A-SIO/0(TM) 
•Full Set of Modem Control Signals, including Rl (Ring Indicator) 
•Easily Configurable to Any Type of Terminal Interface 
•I/O Servicing Environments: (1) Polled; (2) Bus Vector; 

(3)Z80 Mode 2 Vector 

•Off-Board Interrupt Daisy Chain Capability 
•Special Receive Conditions: (1) Framing Error; (2) Parity 

Error; (3) Receiver Overrun Error 

•Baud Rates Selected Individually from 50 Baud to 300K Baud 
•72 Hour Burn-In 




imimimiiiiiiiiiiHiiiiimiimmmigmii 



Z-80A/I-0 

•A complete single board Z-80A CPU with serial/parallel interface 
•Fully compatible with the proposed IEEE S-100 Bus Standard 
•Z-80A CPU (4MHz version of the Z-80) 
•158 instructions— superset of and upward compatible from the 

8080's 78 instructions 
•Up to 4K of on board Eprom with optional Z-80 monitor program — 

1K(2708), 2K(2716) or 4K(2732) 
•Full vectored interrupt capability 
•2MHz or 4MHz operation is jumper selectable 
•Selectable auto-wait state insertion for extending M1", MREQ*, 

IORQ* and/or on board ROM 
•Dual RS-232 serial I/O ports using the Z80A-DART with individual 

baud rate selection (16 baud rates from 50-19,200 baud) 
•Up to 24 bit parallel I/O port— fully programmable Intel 8255A 
•Up to 8 separate counter/timers using 2 Z-80A CTC 
i n 

MICROBYTE 

1198 E. Willow St., Signal Hill, CA 90806 • (213) 595-8571 

D Please send me information on becoming a 
Microbyte dealer. 



I 



. DPIease send info on the Microbyte 

I 

I 

I Name 



Address. 
City 




DISK CONTROLLER 

•DMA to within 16M byte of memory 

•State-of-the-art NEC765 LSI Controller 

•IEEE-S100 compatible 

•DMA arbitration allows use of multiple boards within a system 

•PLL data recovery for totally reliable operation 

•Write pre-comp switched at mid-disc for reliable double density 

operation 

•Supports up to four (4) drives 
•Power On, Power Off or Reset deselects drives to avoid 

damaging files 

•Drive deselect Time Out, deselect drives not in use 
•Single or double sided operation 
•Single density/double density operation 
•8" standard drives 
•Separate Vcc supply for data recovery to eliminate possible noise 

problems 




.State. 



Zip. 



i 



64K DYNAMIC RAM BOARD 

•Fully S-100 bus compatible/Alpha Micro compatible 

•64K x 8 bit dynamic RAM 

•Low power: + 8VDC @ 700 ma 

4- 16VDC @ 100 ma 

- 16VDC @ 25 ma 
•Built-in-parity with LED indicator and vector interrupt 
•Memory addressable in four 16K banks 
•Hidden refresh 

•Gold contacts for high reliability 
•72-hour Burn-in 

•Memory mapped via DIP switch 
•Built-in programmable write-protect 
•Programmable control port for parity and bank control 



It takes more than an initial low price to make 
an S-100 board a profit generator for a dealer. It 
takes a total value cluster from the manufac- 
turer — a value cluster that includes: 

• Products • 

• Price * 

• Quality • 

• Pre-sale Service • 

• Post-sale Service • 

• Commitment • 
MICROBYTE has the products — from memory 
boards to complete S-100 systems, and weoffer 
the rest of the value cluster — call today for the 
whole story on how you can become a Micro- 
byte dealer. 



Circle 97 on inquiry card. 



BYTE February 1981 147 



read and write operations are not be- 
ing executed, thus allowing a refresh 
operation to take place without re- 
quiring the processor to wait. The 
result is that the system is not slowed 
down by the necessary refresh cycles. 
A different type of ref resh must be 
done whenever the RESET or 
pWAIT (S-100 bus) signals are active 
for any extended period of time (more 
than several tens of microseconds). 
These conditions occur whenever the 
system-reset switch is activated or 
whenever a disk access to certain disk 
controllers is being performed using a 
programmed I/O interface. Either of 
these conditions stops the processor- 



generated timing that is required by 
the memory board for transparent 
refresh. Thus, the occurrence of 
either of these conditions must cause 
the memory board to enter an 
automatic refresh mode that con- 
tinues until the processor again starts 
its generation of the timing signals. 

Another feature that most memory 
boards incor porate is the use of the 
PHANTOM signal from the S-100 
bus. This allows read-only memory 
on the disk controller or other board 
to overlay the system programmable 
memory to load an initial program 
from disk. 

Other features to look for include 



input filters on the address and con- 
trol lines followed by Schmitt- 
triggered input gates. This minimizes 
the false starting of memory cycles 
due to noise on the bus signals. Good 
logic design also dictates the use of 
clocked-logic or precision-delay lines 
for the generation of internal- 
memory timing, but under no cir- 
cumstances should RC (resistor/ 
capacitor network) circuits be used 
between logic gates to generate 
delays. Products using this technique 
are unstable under many operating 
and manufacturing conditions and 
can only cause eventual trouble. 
One other important requirement 



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of dynamic-memory boards is good 
documentation. This should include 
board set-up documentation, detailed 
theory of operation, schematics, tim- 
ing diagrams for the different 
processor-board types, a parts list, a 
board-layout drawing, and applica- 
tions notes. 

Finally, the dynamic-memory 
board should be backed up by the 
manufacturer through both guarantee 
and applications support. Several of 
the available memory boards come 
with a full one-year guarantee. The 
manufacturer should also be able to 
support the product with the 
necessary applications information to 



determine if it will work in your par- 
ticular system. 

Limitations of Dynamic Memories 

Although dynamic memory usual- 
ly represents the best cost /perfor- 
mance ratio, there are several limita- 
tions that may prevent it from func- 
tioning correctly. The system 
designer should investigate these 
cases with the memory-board 
manufacturer before deciding to use a 
product. 

It should be apparent from the 
above discussion that not all 
dynamic-memory boards will work 
with all processor boards. Only the 



manufacturer can tell you if the 
memory board has been tested with 
the particular processor board you 
are planning to use. 

Another troublesome area is in in- 
terfacing with DMA controllers. 
Generally, the problems arise from 
two different sources. First, the actual 
timing required from the DMA con- 
troller will vary depending on the 
particular memory board used. Not 
all memory boards use the same 
S-100 bus signals, thus complicating 
the DMA interface. If this timing is 
not compatible, then the memory 
read or write cycles will not function 
correctly. 



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The second trouble area involves 
the correct refreshing of the memory. 
The majority of the dynamic-memory 
devices used today are the 4116-type, 
which require 128 refresh cycles every 
two milliseconds. This requirement is 
easily met when the processor con- 
trols the bus and the memory board 
uses transparent refresh. However, 
when the DMA controller takes over 
the bus, most memory boards will 
cease to do refresh cycles. If the DMA 
controller has access to the bus for a 
small number of byte transfers, this 
does not present a problem. 

A problem may exist, however, 
when the DMA controller does a 
burst sector or track transfer. This 
may prevent refresh from occurring 
for too long a time interval, causing 
the memory to lose data. Some DMA 
controllers, particularly hard-disk 
controllers, avoid this problem by 
doing the DMA transfer to an on- 
board sector buffer consisting of 
static memory. Memory or I/O move 
instructions are then used to transfer 
the data in this memory to the system 
memory. Again, it is important to 
check with the memory-board 
manufacturer for compatibility with 
the DMA controller you plan on us- 
ing. 

One last area of concern involves 
interfacing with a front-panel type of 
system. Extra circuitry is required for 
a dynamic-memory board to correct- 
ly work with the front-panel func- 
tions such as examine, deposit, and 
run. Many memory-board manufac- 
turers do not include this necessary 
circuitry so that they may add other 
functions that they think are more 
valuable in their intended 
marketplace. If you need this func- 
tion, check with the memory-board 
manufacturer. 

In summary, the dynamic-memory 
board represents a superior cost /per- 
formance ratio when compared to 
static memories. When looking at 
dynamic-memory boards, choose one 
that is optimized for your particular 
application, whether it be a single- 
user or multi-user system. It is also a 
good policy to check with the 
memory-board manufacturer before 
your purchase to verify that the 
board will work correctly in your 
particular system. You are best pro- 
tected by a good return policy in case 
you experience any problems after 
testing the memory board. ■ 



150 February 1981 © BYTE Publications lnc 



Circle 98 on inquiry card. 



The first personal computer 
far under $200. 



The Sinclair ZX80. 
A complete computer- 
only $199 . 95 plus $5. 00 shipping. 

Now, for just $199.95, you can get a 
complete, powerful, full-function computer, 
matching or surpassing other personal 
computers costing several times more. 

It's the Sinclair ZX80. The computer that 
"Personal Computer World" gave 5 stars 
for 'excellent value.' 

The ZX80 cuts away computer jargon 
and mystique. It takes you straight into 
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You simply take it out of the box, con- 
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in an hour. Within a week, you'll be writing 
complex programs with confidence. 

All for under $200. 

Sophisticated design makes the 
ZX80 easy to learn, easy to use. 

We've packed the conventional computer 
onto fewer, more powerful LSI chips- 
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faster version of the famous Z80. This 
makes the ZX80 the world's first truly port- 
able computer (6V2" x 8V2" x \W and a mere 
12 oz.). The ZX80 also features a touch 
sensitive, wipe-clean keyboard and a 
32-character by 24-line display. 

Yet, with all this power, the ZX80 is easy 
to use, even for beginners. 



""••AaCft^m 




Your course in computing. 

The ZX80 comes complete with its own 
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is perfect for both novice and expert. For 
every chapter of theory, there's a chapter 
of practice. So you learn by doing— notjust 
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You'll also receive a catalog packed with 
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Lab. And books, hardware options and 
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ZX80's advanced design features. 

Sinclair's 4K integer BASIC has perfor- 
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larger and more expensive computers. 
■ Unique 'one touch' entry. Keywords 

(RUN, PRINT, LIST, etc.) have their 

own single-key entry to reduce typing 

and save memory space. 




■ Automatic 
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A cursor identifies errors 
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■ Powerful text editing facilities. 

■ Also programmable in machine code. 

■ Excellent string handling capability— up 
to 26 string variables of any length. 

■ Graphics, with 22 standard symbols. 

■ Built-in random number generator for 
games and simulations. 

Sinclair's BASIC places no arbitrary re- 
strictions on you— with many other flexible 
features, such as variable names of any 
length. 

And the computer that can do so much 
for you now will do even more in the fu- 
ture. Options will include expansion of IK 
user memory to 16K, a plug-in 8K floating- 
point BASIC chip, applications software, 
and other peripherals. 

Order your ZX80 now! 

The ZX80 is available only by mail from 
Sinclair, a leading manufacturer of con- 
sumer electronics worldwide. 

To order by mail, use the coupon below. 
But for fastest delivery, order by phone 
and charge to your Master Charge or VISA. 
The ZX80 is backed by a 30-day money- 
back guarantee, a 90-day limited warranty 
with a national service-by-mail facility, and 
extended service contracts are available for 
a minimal charge. 



Price includes TV and cassette connectors, 
AC adaptor, and 128-page manual. 

All you need to use your ZX80 is a standard TV 
(color or black and white). The ZX80 comes complete 
with connectors that easily hook up to the antenna 
terminals of your TV. Also included is a connector for 
a portable cassette recorder, if you choose to store 
programs. (You use an ordinary blank cassette.) 





The ZX80isa family learning aid. ChildrenlOand 
above will quickly understand the principles of 
computing— and have fun learning. 

Master Charge or VISA orders call: 

(203) 265-9171. We'll refund the cost of your call. 
Information: General and technical— (617) 
367-1988, 367-1909, 367-1898, 367-2555. 
Phones open Monday-Friday from 8 AM to 
8 PM EST. 



Sinclair Research Ltd., 475 Main St., 
P.O. Box 3027, Wallingford, CT 06492. 



To: Sinclair Research Ltd., 475 Main St., P.O. Box 3027, Wallingford, CT 06492. 

Please send me ZX80 personal computer(s) at $199. 95* each (US dollars), plus $5 

shipping. (Your ZX80 may be tax deductible. ) 

I enclose a check/money order payable to Sinclair Research Ltd. for $ 



Name_ 



Address _ 
City 



.State. 



_Zip_ 



Occupation: 

Intended use of ZX80: . 



-Age: 



L 



Have you ever used a computer? □ Yes □ No. *For Conn, deliveries, add sales tax. 

Do you own another personal computer? □ Yes □ No. 

BY-2-1 



Stacking Strings in FORTH 



John ) Cassady 

339 15th St 

Oakland CA 94612 



Anyone who is familiar with 
writing programs in BASIC and who 
later switches to writing in FORTH 
surely misses the convenience and 
ease of BASIC string handling. For- 
tunately, there is no need to deprive 
yourself all these features: they can be 
implemented in FORTH with the ad- 
ditional bonus of not being tied to the 
preconceived ideas of your software 
vendor. If you do not like the way the 
string operators work, you can 
change them: you control the source 
code. 

Adding Strings to FORTH 

Tools for manipulating strings of 
characters and other data items are 
useful to the personal computer pro- 
grammer. The routines presented 
here are an extension to FORTH. 
They run in fig-FORTH (the versions 
of FORTH for various microproces- 
sors written by the FORTH Interest 
Group) and should run with little 
adaptation in any standard FORTH. 

String implementations abound in 
FORTH. Some, like the one presented 
here, use stacks. The use of stacks 
seems appropriate in FORTH. Most 
of FORTH programming consists of 
manipulating entities on various 
stacks. 

A stack is a LIFO (last in, first out) 
list. Stacks usually have a fixed 
width; that is, the number of bits that 
are simultaneously pushed (ie: put 
onto the stack) or popped (ie: taken 
off the stack) does not vary. An item 
on the stack is usually limited to some 
maximum size (eg: 16 bits) that can 



represent numbers up to decimal 
65,535. The FORTH parameter and 
return stacks both have fixed widths. 
The string stack is like the para- 
meter stack and the return stack, but 
it is not restricted in width. String- 
stack items can be any width and any 
combination of widths. However, 
item size and total stack size are 
limited only by the amount of mem- 
ory devoted to them. As a rule of 
thumb, a few hundred bytes are more 



than enough. 

Figures 1 and 2 and listing 1 illu- 
strate two ways of visualizing string 
stacks. They show the stacks growing 
downward from high memory. This 
is typical in FORTH. Even though the 
string stack grows downward, we 
will refer to the most recent entry on 
the stack as the top of the stack. The 
unchanging end of the stack (hexa- 
decimal 2000 in figure 2) will be called 
the base. When something is popped 



r~ 





6 


W 


1 


N 


T 


E 


R 


r -1 


( 

GROWS 
DOWN 












N 


\ 

FIXED BASE OF 
STRING STACK $0 





4 


F 


A 


L 


L 






( 


























^ 


r~ 





6 


s 


U 


M 


M 


E 


R 


-J 


(_ 
































/■ 





6 


s 


P 


R 


1 


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HED 

E. 








\ 
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1 


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L 

NEXT ITEM PUS 
WOULD GO HER 


ON 


ST* 


-J 

; 

CK 


THIS ITEM WOULD BE 
PRINTED BY THE FORTH 
WORD {$.} 



Figure 1: One implementation of a string stack in FORTH. As the name implies, a string 
stack is a stack of variable-length strings (as opposed to fixed-length numbers) orga- 
nized such that only the string most recently put on top of the stack can be removed 
from the stack. Each stack entry consists of the length of the string, expressed in 2 bytes, 
followed by the characters of the string itself. Due to an initial design decision, this 
string grows toward low memory locations (ie: down) rather than toward high memory 
locations (ie: up). Despite this physical orientation, the most recently placed string is 
located at the top of the stack — at the lowest address in the stack. 



152 February 1981 © BYTE Publications Inc 



"My computer helped me write 

The Final Encyclopedia. I wouldn't trust 

anything less than Scotch" Brand Diskettes 

to make a long story short!' 




Gordon R. Dickson, 
Science Fiction Author, 
Minneapolis, Minnesota 

Gordon Dickson: a small business- 
man whose product is his own 
imagination. He's written more than 
40 novels and 150 short stories; 
his newest work is The Final 
Encyclopedia. He uses his personal 
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All his words-his product- 
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Circle 99 on inquiry card. 



BYTE February 1981 153 



Circle 100 on inquiry card. 



from the stack, it is the top item (as 
defined above) that is removed. 

A string consists of a 2-byte length 
word followed by the text of the 
string, as you are moving upward in 
memory. Since the length is explicitly 
stated, there is no need for a sepa- 
rator or delimiter. Any of the 256 
possible 8-bit quantities, for example, 
can appear in the string. Strings can 



include binary numbers, floating- 
point numbers, encrypted messages: 
in short, anything that can be stored 
in a byte. 

Before considering routines any 
further, heed the caution that this 
article presents an example of an 
extension to FORTH. It's not the only 
way to implement strings nor, 
perhaps, the best way. The article 



7 7 



$0 ► 



TEXT < 



LENGTH 



TEXT I 



LENGTH 



TEXT ( 



LENGTH 



TEXT I 



LENGTH 

(2 BYTES OR 
1 FORTH WORD) 



ASSUME MEMORY 
ADDRESS 2000 



// 



-MEMORY ADDRESS 19E2 



Figure 2: Another view of the string stack of figure 1. $0isa constant that points to the 
address of the base of the string stack. Here it has the value of hexadecimal 2000. See 
listing 1 for the FORTH dialogue that uses the string stack shown here. 



154 February 1981 © BYTE Publications Inc 






ITION 




VERS 







MM 



: 



'■ 







The Byte Covers shown at left are available as 
Collector Edition Prints. Each full color print is: 

• 11" X 14" including a 1Vz" border. 

■ Part of an edition strictly limited to only 100 
prints. 

• Personally inspected, signed and numbered 
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• Accompanied by a Certificate of Authenticity. 

• Carefully packed and shipped first class. 

• Priced at $20, plus $3 ($6 overseas) for post- 
age and handling. If Set 1-4 or Set 5-8 is 
ordered, the price for all 4 prints is only $70. 

To order, use the coupon below. Visa or Master- 
Charge orders may call Toll Free. 



Please send me the following Collector Edi 
tion Byte Covers and Certificates of Authen 
ticity. 

Qty. Cover Amount 

#1-7 Bridges of Konigsberg $20 

#2-Fun and Games $20 

#3-Homebrev» $20 

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Post. & hand. ($3 in US . $6 overseas) S 



Total 



D I have enclosed check or money order 

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Card # 



Expiration Date 

Send my print(s) to: 

Name 

Address 

City 

State_ 



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'- 80o -<*«-ose^ EE! 



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1864 N. Pamela Dr. 
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70815 



simply illustrates a FORTH program 
and an interesting mixture of two 
quite distinct logical structures: the 
stack and the string. And it has some 
desirable features: it is easy to 
visualize and modify the operations. 

Some String-Manipulation Words 

In listing 2, the word *$* creates a 
constant with a value equal to the size 
of memory to be reserved for the 
string stack during compilation. The 
stack size can be changed simply by 
changing this one value and recom- 
piling. 

The words $0 , $P , and { $P! } are 



direct duplicates of the words SO , 
SP , and { SP! } used in the FORTH 
kernel. The only difference is that 
they operate on the string stack in- 
stead of on the parameter stack. $0 is 
a constant that returns the address of 
the fixed end of the string stack (ie: 
the base) to the parameter stack. (See 
line 4 of listing 2.) This means that the 
value of $0 , the memory address, is 
pushed onto the parameter stack 
when it is used. 

$P is a variable. It is the stack 
pointer. At any given time, it con- 
tains the address of the top string on 
the stack (which is the length word of 



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the top string). When $P is executed, 
it places the address (not the value) of 
the stack pointer onto the parameter 
stack. Therefore, to get the value of 
the string-stack pointer, we need to 
type the following two-word se- 
quence: 

$P @ 

This sequence is reduced to a single 
word $P@ , which is defined at line 7 
of listing 2. Listing 3 shows a FORTH 
dialogue that explains the use of 
VARIABLE , CONSTANT , and @ 
(pronounced "fetch"). 

The word { $PI } empties the 
string stack. [The braces used in 
{ $P! } and elsewhere in the article 
are not part of the FORTH word. 
Following a convention set in the 
August 1980 BYTE, braces are used to 
surround a FORTH phrase or a 
FORTH word that contains a punc- 
tuation mark GW] It does this by 

placing the value for the base of the 
string stack onto the parameter stack 
and making it the current value for 
the string-stack pointer. The word 
{ $PI } is the first colon definition en- 
countered. The words CONSTANT , 
VARIABLE , and { : } compile 
words into the FORTH dictionary. 

Our next definition, in line 8 of 
listing 2, is $DROP . This will drop 
(ie: delete) the string on top of the 
string stack. It may seem we are get- 
ting ahead of ourselves — after all, 
we are defining $DROP before we 
define any word that puts strings on- 
to the string stack. But this is okay as 
long as we don't use any undefined 
words inside the definition. FORTH 
compiles its words in one pass, and it 
won't give us an error message as 
long as we don't give it a word it 
doesn't recognize. 

If we "walk" through $DROP , we 
see that the value of the string-stack 
pointer is placed on the parameter 
stack by the word $P@ . It is then 
duplicated by the word DUP , leav- 
ing two copies. The top copy of the 
address is replaced by the contents of 
the location pointed to when the 
word @ is executed. This places the 
length of the top string on the para- 
meter stack. The word + adds this 
length to the value of the stack 
pointer, and 2+ increments that 
result by 2. The value on top of the 
parameter stack is now the address of 
the word containing the length of the 
second string on the string stack. 



156 February 1981 © BYTE Publications Inc 



The sequence { $P ! } is a two-step 
process that places the address of the 
variable containing the string-stack 
pointer on the parameter stack and 
storing the new value into it. Thus, 
after executing $DROP , the string- 
stack pointer is changed to point to 
what was the next-to-top string. This 
effectively drops the top string, even 
though there was nothing changed in 
the contents of the memory buffer 
devoted to the string stack. 

This definition of $DROP is not 
entirely adequate. If you execute this 
word with an empty string stack, 
there is a good chance of moving 
your string-stack pointer into a 
memory area where it doesn't belong. 
To avoid this, additional code must 
be added. The word $DROP should 
check that the stack is not empty 
before it executes. Safeguards of this 
nature are appropriate in many of 
these routines. To include them in 
this article would, however, need- 
lessly complicate the description of 
the words. 

Loading, Storing, and Printing 
Strings 

The word $@ (line 9 of listing 2) is 
the first that expects parameters on 
the parameter stack. It expects a text 
address as the second stack item and a 
quantity on top of the stack. The text 
address points to a memory location 
of the first byte of the string that will 
be moved to the string stack. The 
quantity is the length of the string. 
Thus, if the expression "the quick 
brown fox" was residing in memory 
starting at hexadecimal location 2C80 
and we wanted to move it to the 
string stack, we would type the 
following sequence: 

2C80 13 $@ 

with the hexadecimal 13 (or decimal 
19) being the length of the string. The 
quantities could be in decimal if the 
FORTH word BASE has been set to 
decimal. 

The word { $! } complements $@ . 
It takes the string on top of the string 
stack and moves its text to whatever 
memory location is addressed by the 
top of the parameter stack. Thus, the 
string can be moved into a string 
variable, to an output buffer, or to a 
memory-mapped video display. 

To print a string we use the two- 
character word { $. } (pronounced 
"string dot"). This follows the 



FORTH convention of using dot for 
output. It also uses the FORTH oper- 
ator TYPE to accomplish it. 

$DUP (line 13 of listing 2) is shown 
as an example of one of several 
operators that might be written to 
manipulate string-stack items. Useful 
additions are $SWAP and $OVER. 
The need could also arise for a 
$ROT , although I've never wanted 
it. $DUP simply gets the length and 
location of the current top string on 
the string stack and executes $@ . 

For a truly useful system, we want 
a person to sit at a keyboard and be 
able to type a sentence directly to the 



string stack. This and more is accom- 
plished by the one-character FORTH 
word { " } (pronounced "quote"). 
The techniques used in quote are ex- 
actly the same as in the fig-FORTH 
message-handler word { ." }. This 
word (pronounced "dot quote") is a 
period followed by a double quote 
mark. This word checks to see if we 
are interpreting from the keyboard or 
compiling a definition. If we are inter- 
preting, it accepts input until it 
detects another quote, then moves the 
text between the two quotes to the 
string stack. If we are compiling a 

Text continued on page 162 



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Listing 1: Manipulating the string stack and string pointer. Figures 1 and 2 show the 
state of the string stack at the beginning of this dialogue. Here and in following listings, 
user input is underlined and computer response is not. See listing 3 for further details on 
the FORTH word @ (pronounced "fetch"). 



Dialogue With Computer 
HEX OK 

$0 . 2000 OK 

$P @ . 19E2 OK 
$P @ @ . 6 OK 



%_ SPRINGOK 

$0 . 2000 OK 

$P @ . 19EA OK 
$P @ @ . 6 OK 



t SUMMEROK 
S^FALLOK 
$. WINTEROK 



Commentary 

All numbers will be expressed as 
hexadecimal. 

Base of string stack is hexadecimal 
2000. 

Location pointed to by stack pointer $P. 

Contents of location (length word of string 
on top of stack). 

Print top string; notice no space between 
STRING and prompt OK. 

The base of the stack hasn't changed. (It's 
a constant.) 

But the stack pointer has changed. 



Print the next three strings, 
popping them from the string stack. 



Listing 2: Defining string-manipulating words. See text for details. 




1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 



( FORTH STRING STACK EXTENSION 
HEX FORTH DEFINITIONS 



FIGFORTH1.1 ) 



200 CONSTANT *$' 
*$* ALLOT ( LEAVE 
HERE CONSTANT $0 
$0 VARIABLE $P 
$P! $0 $P ! 
$P@ $P @ ; 
$DROP $P@ DUP 
$@ DUP >R $P@ 

SWAP - SWAP 
$! DUP 2+ SWAP i 
$. $P@ DUP 2 + 
$DUP $P@ DUP 



(NUMBER OF BYTES RESERVED FOR $STK 

IN THE DICTIONARY OF *$' BYTES FOR $STK 

( $0 RETURNS FIXED BASE OF $STK TO PSTK 

$P RETURNS ADDR OF VAR HOLDING $STK PTR 

( $P! EMPTIES $STK BY RESETTING $P TO $0 

( $P@ RETURNS VALUE OF $P TO PSTK 

(- 2+ $P ! ; ( DROP TOP STRING 

TA - 2 QTY - 1 FETCH STRING TO $STK 

R CMOVE 2 - R> OVER ! $P ! ; 

SWAP CMOVE $DROP ; ( ADDR - 1 

TYPE $DROP ; ( OUTPUT STRING 
@ $@ ; ( DUPLICATE STRING 



GAP 



( 
OVER 
) ROT 

SWAP @ 
2+ SWAP 



Listing 3: A dialogue that explains the FORTH words CONSTANT , VARIABLE , @ , 
and { . }. The main point to remember is that when you name a constant, its value is 
put on the stack; but when you name a variable, the address that contains the value is 
put on the stack. 



Dialogue With Computer 
100 CONSTANT CON OK 

100 VARIABLE VAR OK 
CON OK 



100 OK 



VAR OK 
. 6480 OK 



Commentary 

Defining CON = 100. 

Defining VAR = 100. 

Put value of constant onto stack; 

print value on top of stack, remove from 

stack; therefore, 100 is value of CON. 

Put address of variable onto stack; 
print value on top of stack, remove from 
stack; therefore 6480 is the memory loca- 
tion at which the value of VAR is stored. 

Listing 3 continued on page 160 



158 February 1981 © BYTE Publications Inc 



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Listing 3 continued: 

VAR OK 
@ OK 

_^100 OK 

VAR @ . 100 OK 
VAR ? 100 OK 



The address of VAR is on the stack. 

@ replaces the address with its contents. 

The value of memory location 6480 should 

now be on top of the stack. 

It is; this shows that VAR stores the 

value 100. 

This can be done on one line 
{ ? } is the same as { @ . } 



Listing 4: More string-manipulating words. 





1 

2 

3 

4 

5 

6 

7 

8 

9 

10 

11 

12 

13 

14 

15 



FIGFORTH1.1 
MOVES IN-LINE STRING TO SSTACK 



FORTH STRING STACK EXTENSION 
(") R DUP 2+ SWAP @ ( 

DUP 2+ R> + >R $@ ; 

( IF COMPILING EMPLACE AN IN-LINE STRING TO 

( BE MOVED TO STRING STACK AT EXECUTION TIME 

( ELSE PUT ENCLOSED STRING ON STRING STACK 



22 STATE @ 
IF COMPILE ( 

- 1 ALLOT 
ELSE C, WORD 

HERE DUP 2 + 



) C, WORD 
DUP , ALLOT 
HERE C@ 
SWAP @ $ 



HERE Crj 



1 ALLOT HERE ! 



ENDIF 



IMMEDIATE 



Listing 5: More string-manipulating words. 

( FORTH STRING STACK EXTENSION FIGFORTH1.1 

1 0E + ORIGIN @ CONSTANT BS ( SYSTEM BACKSPACE CHARACTER = 8 

2 7F CONSTANT PBS ( BYTE USED BY POLY 88 MONITOR AS BACKSPACE 

3 : SINPUTPADDUP ( RTNS TEXT DELIM BY CR FROM KEYBRD TO $STK 

4 BEGIN KEY DUP BS = ( IS IT A BACKSPACE? ) 

5 IF( BS ) >R 2DUP = R> SWAP ( AND AT START OF BUFFER? 

6 IF DROP 

7 ELSE DROP PBS EMIT 1 - 

8 ENDIF 

9 ELSE ( NOT BS ) DUP OD = ( IS IT A RETURN? ) 

10 IF DROP 20 EMIT 1 

1 1 ELSE DUP EMIT OVER C ! 1 + 

12 ENDIF 

13 ENDIF 

14 UNTIL OVER - $@ ; 

15 ;S 



Listing 6: Defining a word to get the date from the keyboard. This word, GETDATE , 
prompts for and will accept only an input of exactly seven characters. 



FORTH Statements 

7 SVARIABLE TDATE 
: GETDATE 
BEGIN 

$P! CR 

" Input today's date (DDMMMYY): " $. 

SINPUT 



7 = 
UNTIL 



Commentary 

Begin definition of word GETDATE. 

Start BEGIN. ..UNTIL loop. 

Clear string stack. 

Output message. 

Accept input from keyboard. 

Push length of string onto stack. 

Compare to 7. 

Loop to BEGIN if length of string * 7. 

Listing 6 continued on page 162 



160 February 1981 © BYTE Publications Inc 



Circle 103 on inquiry card. 



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We know 
the Atari 800. 



The experts at ComputerLand 
would like you to meet the com 
puter that leads two lives. By 
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^B sophist: 

Let tis 



keep tax records, analyze 
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Circle 104 on inquiry card. 



BYTE February 1981 



163 



Articulate Automata: 

An Overview of Voice Synthesis 



Kalhryn Fons and Tim Gargagliano 
1394 Rankin St 
Troy MI 48084 



The time has arrived for computers to begin speaking 
for themselves! We discussed some basic techniques for 
using the TRS-80 Voice Synthesizer in the October 1979 
BYTE ('The TRS-80 Speaks," page 113). Response from 
readers showed many were interested in a more detailed 
look at voice synthesis. The information presented here is 
concerned with the basic theory of voice synthesis and 
the basic procedures involved in constructing a vocabu- 
lary. The type of synthesis we focus on is electronic 
phoneme synthesis. A phoneme is a basic unit of sound 
from which speech can be constructed. 

Voice-Synthesis Technology 

During the past two decades, almost every aspect of 
computer technology has progressed through several 
generations of advancement. A relatively recent addition 
to this list is speech synthesis. The area of computer 
technology which would seem to gain most from speech 
synthesis is the man-to-machine interface. This is an area 
which remains in need of a great deal of development. 
Today, computers play a role in almost everyone's life, 
yet we rely on a group of specialists to control the com- 
puters. If computer technology is to continue to advance, 
there will be a strong need for the inexperienced user to 
communicate directly with the computer. It seems ob- 
vious that the man-to-machine interface will be one of the 
biggest challenges facing this industry in the 1980s. 

Another problem confronting computer users is visual 
confusion and/or saturation. This can occur after watch- 
ing a video monitor or scanning a printout for hours at a 
time. Part of this problem can be eliminated by including 
a nonvisual output channel in the computer system. The 



About the Authors 

The authors are both employed by the Votrax Division of Federal 
Screw Works in Michigan. Kathryn Fons is a speech scientist; Tim 
Gargagliano is a computer engineer. Both have done extensive research 
in language-processing systems and have worked on the Votrax text-to- 
speech algorithm. They have a special interest in voice synthesizers in 
relation to the needs of the handicapped and invite inquiries at the ad- 
dress shown above. 



obvious choice is voice, since most people normally com- 
municate verbally. In a number of situations, the serial 
nature of voice output is more desirable than parallel 
data from a printout or video screen. 

A number of applications are already using voice syn- 
thesis. Among these are telephone order-entry systems, 
telephone access systems, reading machines and ter- 
minals for the blind, communicators for the verbally im- 
paired, and computerized dispatching. 

Physiology of Speech 

The production of speech in the human vocal system 
begins with a source of acoustical excitation to drive the 
vocal tract. There are two kinds of excitation: periodic 
and random. The first type of excitation is a pulse train 
caused by the vocal folds blowing apart and collapsing 
under lung pressure (see figure 1 on page 166). The pulse 
train is rich in harmonic content due to its sharp wave 
shape. The second type of excitation is noise (frication) 
caused by air passing over the articulators (tongue, 
cheeks, lips, teeth, etc) with the vocal folds open. 

Phonemes containing periodic excitation are called 
voiced phonemes (eg: the vowel I a I). Phonemes contain- 
ing only frication are said to be unvoiced (eg: the conso- 
nant ///). It is also possible for a voiced phoneme to con- 
tain frication (eg: the consonant Izl). 

The human vocal tract is formed from resonant 
cavities including the mouth and nasal cavities which re- 
spond to input excitation by filtering the input. At any 
given time, placement of the articulators determines the 
frequency response of the vocal tract. Generating speech 
from the input excitation involves sequentially varying 
the frequency response of the resonant cavities in the 
vocal tract. This is done by movement of the articulators. 
The vocal tract is a fairly complex time-variant filter net- 
work. 

Speech is composed of several bands of frequencies 
called formants (see figure 2). Each formant varies in 
position, amplitude, and quality with respect to time. A 
static sound, such as a continuous vowel, is produced by 
moving the air through the vocal tract and over the ar- 
ticulators, which are appropriately positioned to create 



164 February 1981 © BYTE Publications Inc 



Circle 105 on inquiry card. 




THIS COULD BE THE START OF 
SOMETHING SMALL. 



At Micropolis, we make a big 
deal over our small deals, too. 

Because we believe there 
should be a place in the mar- 
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When you ask us for help, we 
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The single fact is, nobody 
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When you deal with Micropo- 
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inconvenience and delay of try- 
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interfacing and system software 
development. 

For more information about 
our system integrator program, 
call Jim Molenda at extension 330. 
He'll be glad to tell you all about it. 

Because we're Micropolis. 

And we've got big ideas for 
small system integrators. 



MICROPOLIS 

In the US: 21329 Nordhoff Street. 
Chatsworth, CA 91311 • 213/709-3300 
In Europe: Micropolis International 
(U.K.) 0734-860817 Telex 851847395 



Circle 106 on inquiry card. 



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Like Lightning! 



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Proforma Income Statement and Balance Sheet 



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Capital Investment Analysis 



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Depreciation Method Comparison 



Histogram Formed From Set of Numbers 



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Lease/Buy Analysis 



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Sales Manager's Information System 



In BASIC — Source Listings 
Licensing Only 

Send for Our Catalog 



i 



« 



oho oqrrq prooucti ODSpotpTnon 

14600 Detroit Avenue • Lakewood, Ohio 44107 
Call [216] 221-9000 



I 
J 



(la) 



/ \ 




/l[\ 




y \ 



COLLAPSED 

PRESSURE 
BUILDS 


BLOWN APART 

VOLUME OF 
AIR EMITTED 


COLLAPSED 

PRESSURE 
BUILDS 


(lb) 

AIR 
PRESSURE 







Figure 1: Periodic excitation of the human vocal tract starts 
with the vocal .folds repeatedly opening and closing (la), 
regulating air flow from the lungs. This results in a pulse train of 
air (lb) which passes through the resonant cavities of the mouth 
and nasal passages. 



AMPLITUDE 




F0RMANT 1 
CENTER FREQUENCY 



F0RMANT 2 
CENTER FREQUENCY 



FREQUENCY 



Figure 2: Speech is composed of several bands of frequencies 
known as formants. Shown is a generalized formant envelope 
for the first two formants. 



that sound. During the production of a word, the ar- 
ticulators are constantly moving from one phoneme posi- 
tion to another. This sequencing of the articulator move- 
ments is one reason why each sound in the sequence in- 
fluences every other sound around it. Note that the 
change in articulator positions does not occur in a single- 
step fashion, but rather in a continuous movement from 
one target position toward another. The frequency 
response of the vocal tract is in flux between the target of 
the last phoneme and the current phoneme. The acous- 
tical changes that occur during the transition are referred 
to as dynamic articulations. They are important to the 
production of intelligible speech — human or synthetic. 
Without dynamic articulation, speech becomes choppy 
and often unintelligible. 



166 February 1981 © BYTE Publications Inc 



Circle 107 on inquiry card. 



Circle 108 on inquiry card. 



Q«MC 



THE DIFFERENCE BETWEEN TOYS AND 
TOOLS IN MICROCOMPUTERS AND 
COMPONENTS. 



17 7/8 W x 11 3/8 H X 18 3/4 D 

SI 00 bus 

IEEE Std. Z80 processor card 

Shugart SA1004 Winchester disk (8.4 

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Shugart 801 R 8" Floppy disk drive for 

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64KB Dynamic RAM 

2 Serial and 3 Parallel Ports 

CP/M 2.2 Operating System - Std. 

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OASIS Multiuser operating system - 

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17 7/8 W x 11 3/8 H x 18 3/4 D 

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2 Serial and 3 Parallel Ports 

CP/M 2.2 Operating System - Std. 

Complete Documentation 

OASIS Multiuser operating system ■ 

optional 

LIST PRICE $4,450 



SYSTEM 80W 




SYSTEM 80 




NNC Z80 CPU Board 




Totally IEEE SI 00 Standard 

2 Serial Ports 

3 Parallel Ports 
Vectored interrupts 
Real time clock 

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Photo 1: A selection of voice synthesizers. Top left: Votrax ML- 
I multilingual synthesizer. Bottom left: phonetic keyboard for 
controlling a synthesizer without the use of a computer. Right 
top to bottom: Radio Shack TRS-80 Voice Synthesizer, Votrax 
VS6 synthesizer, Votrax VSK single-board voice synthesizer. 
Not shown: Votrax SC01 single-chip voice synthesizer. 




Photo 2: An electronic analog of the human vocal tract using 
filters, oscillators, and noise-source modules. Control of these 
circuits requires an understanding of the static and dynamic 
parameters of human speech. 




Photo 3: A spectrum analyzer display of a static phoneme. The 
X axis is frequency; the Y axis is amplitude. 



The Electronic Equivalent of the Vocal Tract 

An electronic analog of the human vocal tract can be 
constructed using filters, oscillators, and noise-source 
modules (see photo 2). Control of these modules is com- 
plicated, and requires measuring the static and dynamic 
parameters of human speech. 

The study of speech parameters requires some complex 
instruments. Speech is most frequently considered in 
terms of frequency composition, rather than waveforms 
measured as a function of time. Therefore, analysis of 
speech is typically carried out in the frequency domain. 
This requires instruments that are able to measure and 
plot frequency, amplitude, and time in various relation- 
ships. A spectrum-analyzer scope can display a picture of 
amplitude versus frequency for an instant in time (see 
photo 3). This provides accurate measurement of energy 
distribution among the frequencies of a static sound. 

Another type of spectrum analyzer used in the study of 
speech is a voiceprint machine. This device provides a 
picture of amplitude versus frequency versus time which 
is collapsed into two dimensions (see photo 4 on page 
172). This type of printout allows us to study the dynam- 
ic characteristics of speech, such as phoneme duration 
and dynamic articulations. Notice how the frequencies 
continuously move during the transition from one pho- 
neme to the next. 

The area of computer technology 

that stands to gain most from 

speech synthesis is the 

man-to-machine interface. 

With these instruments, measurements can be made of 
the center frequencies of formants, their amplitudes, and 
their bandwidth. These measurements are the basis for 
designing the filter networks used in an electronic vocal 
tract. A model of a voice synthesizer in its simplest form 
is shown in figure 3. Depending on the desired speech 
quality, a varying number of parameters must be con- 
trolled. The number of bits stored for each parameter 
depends on the needed range and quantization tolerance 
of each parameter. To control this type of synthesizer, 
parametric data must be updated every 5 to 25 ms. The 
update frequency must be high enough to capture the 
parametric movements during phoneme transitions. 
While this synthesizer model can provide much flexibili- 
ty, it does so at the expense of a high bit-rate/storage re- 
quirement and complex vocabulary generation. 

The Votrax Phoneme Synthesizer 

A phoneme synthesizer can be modeled by adding a 
parametric control generator and a dynamic-articulation 
control unit. A model for a Votrax phoneme synthesizer 
with several options is shown in figure 4 on page 174. 
Rather than have the user update all the parameters of a 
phoneme several times during its production, the syn- 
thesizer automatically does it using an internal algorithm. 
Because the Votrax phoneme synthesizer is implemented 
totally in hardware, there is no requirement for an exter- 
nal computer/memory to generate phonemes. 

A high-quality phoneme synthesizer (with many inter- 
nal parameters) is no more complex for the user to con- 



170 February 1981 © BYTE Publications Inc 



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Photo 4: A voiceprint of the message "hello readers. " The X axis is time; the Y axis is frequency. Amplitude is displayed as a function 
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/rite pi | ^> 



WRITE PN I ^> 



PARAMETRIC 



RAMETRIC I v. 

DATA BUS I y 




-A 



FS- FRICATIVE EXCITATION SOURCE 
PS- PERIODIC EXCITATION SOURCE 
FN- FILTER NETWORK 
a- VARIABLE AMPLIFIER GAIN 



Figure 3: A parametric speech synthesizer. The number of bits stored for each parameter depends on the needed range and the quan- 
tization tolerance of each parameter. In order to control this type of synthesizer, parametric data must be updated every 5 to 25 ms. 



172 February 1981 © BYTE Publications Inc 



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BYTE February 1981 173 





f 


01 

o 

H 
< 

at 

LU 
Z 
UJ 

o 

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o 

ft: 

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o 
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ft: 
1- 
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ft: 

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PHONEME 
COMMAND WORDS 


N 

P 
A 
R 
A 
M 
E 
T 
E 
R 
S 


• 

• FILTER CONTROL 
PARAMETERS 

• 












PHONEME 










SELECT < 






• • • 
' J 




6 BITS 
























FN 






( 








X< 








FS 




«r> — ► 




























«^_rf 








psh 


a2^> — •> 




st 






f 
































OPTIONAL 




,, 




PITCH / 


* 


• 














2-3 BITS 










AMPLITUDE 


1 










1 BIT 










RATE 
2 BITS 








1 * 


•S- FRICATIVE EXCITATION SOURCE 




I * 




3 S- PERIODIC EXCITATION SOURCE 
FN- FILTER NETWORK 
a- VARIABLE AMPLIFIER GAIN 










, 


r 








TIMER 


DUR 


ATION 

r 




PHONEME 


* 




REQUEST 

























Figure 4: A basic Votrax voice synthesizer. A phoneme command word is presented to the unit on the positive edge of the phoneme- 
request signal. The parametric control generator greatly reduces the synthesizer data consumption by calling out N parameters from 
only 6 bits. The dynamic-articulation controller generates continuous parametric transitions at phoneme boundaries. 



trol than a minimal unit because both utilize the same 
phoneme call-out procedure. A command word is used to 
signal phoneme production. The command word for a 
phoneme includes phoneme-select data and optional 
pitch, rate, and amplitude data. Typically, there are 
sixty-four phonemes produced, each requiring a 6-bit 
command word. 



There are areas where a person 

must interact with a computer, but 

where the use of a visual output 

channel is inappropriate, 

unavailable, or ineffective. 

A simple digital controller or microcomputer is all that 
is needed for vocabulary retrieval. In the phoneme syn- 
thesizer we have modeled here, the duration of each pho- 
neme is controlled by an internal timer. At the end of an 
interval, the timer output momentarily goes low, request- 
ing the interface to send the next phoneme command 
word. This phoneme request signal can be used to gener- 
ate an interrupt request to a microprocessor or clock a 
command word out of a FIFO (first-in/first-out) buffer, 
an interface, or ROM (read-only memory). See figure 5 
on page 176. 



Several types of Votrax synthesizers are available. A 
recent addition to this family is the SC01, the first single- 
chip phoneme synthesizer; it represents a significant 
breakthrough in speech-synthesis technology. Contained 
in a 22-pin dual-inline package, this low-power CMOS 
(complementary metal-oxide semiconductor) synthesizer 
can be easily used on a printed-circuit board. Latched 
parallel inputs permit direct connection to a microcom- 
puter data bus. A master clock input on the SC01 permits 
a variety of voice effects and highly textured sound ef- 
fects to be generated. 

Phonetic Programming 

There are a few specific speech rules that dictate how 
phonemes are sequenced for intelligible speech output. 
Pronunciation guidelines and symbols, established by the 
IPA (International Phonetic Association), are often used 
to identify the phonemes and the altered or adapted units 
of sound (called allophones). These are used because the 
standard alphabetic characters may have more than one 
sound associated with a single symbol. Using phonetic 
guidelines, phonemes and/or allophones are combined to 
form the symbol sequence that represents the spoken 
word in a language. The written symbology, however, 
does not always directly translate into the sounds avail- 
able in a phoneme synthesizer. Thus, a sequence of the 
synthetic phonemes constructed from the phonetic guide- 

Text continued on page 180 



174 Febraary 1981 © BYTE Publications Inc 



Circle 112 on inquiry card. 




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(5a) 



L— NEW PHONEME 



■ NEW PHONEME 



(5b) 



DATA 
WRITE 



V 



DATA DATA 

IN F | F0 OUT 



SHIFT 
IN 



SHIFT 
OUT 



PHONEME 
COMMAND 



PHONEME 
SYNTHESIZER 



PHONEME 
REQUEST 



(5c) 



OUTPUT 
PORT 



COMPUTER 
DATA BUS 



A 



LATCH 



PHONEME 



WRITEl •*" 



IRQ' 



Lt 



Q CLR D 
Q CK 



FLIP-FLOP 



PHONEME 
COMMAND 



PHONEME 
SYNTHESIZER 



PHONEME 
REQUEST 



Figure 5: Interface characteristics. A new phoneme is sent on 
the positive edge of the phoneme-request signal (5a). A FIFO 
(first-in/ first-out) shift register (5b) provides an elastic buffer by 
shifting data in at a rate independent from the data being shifted 
out. Phoneme-request (5c) sets a flip-flop which generates an in- 
terrupt request (IRQ) to the microcomputer. When the com- 
puter writes the next phoneme command into the latch, the flip- 
flop is reset. 



Programming Phoneme Voice Synthesizers 

There are a number of steps involved in program- 
ming a voice synthesizer. Initially, you will probably 
have to frequently refer to table 1, which lists symbols 
and example words which represent sounds: 

•Select the words to be programmed. 

• Speak the words out loud. 

• Select the appropriate phonetic symbols to represent 
the sounds in the words. The number of phonetic sym- 
bols you use should equal the number of sounds 
counted when the words are spoken. 

• Enter the phoneme sequence into the synthesizer and 
listen to the speech output. Check the synthesizer's 
pronunciation for the appropriate duration of each 
syllable and rhythm of each word. The accent (or 
stress) placed on each word or syllable will help define 
the duration parameter. 

• Select the longer-duration vowel phoneme for the 
accented syllable and the shorter-duration vowel 
phoneme for the unaccented syllable. Reenter the pro- 
gram and listen to it again. 

• Adjust the program as many times as needed to 
achieve the desired pronunciation. This can be done 
by selecting different vowel-phoneme durations for the 
stressed vowel so that the durational relationship be- 
tween the syllables sounds correct (see table 3). You 
can also adjust the sound by inserting a transition 
allophone between main vowels and consonants to 
achieve smooth pronunciation (see tables 2 and 3). 



A few examples are: 

Word Initial Program 

move M-U-V 
family F-AE-M-L-E1 



Refined Program 

M-U1-U1-V 
F-AE1-EH3-M-L-Y 



harvest H-AH-R-V-I3-S-T H-AH1-UH3-R-V-13-S-T 



Phonetic Symbols 




Key Words 




Phonetic Symbo 


s 




Key Words 


Votrax 




IPA 






Votrax 


IPA 






B 




b 


bat - rub 




NG 


rj 




ring - drink • single 


D 




d 


dad - raid 












G 




9 


get - log 




R 


r 




race - hard - hair 


P 




P 


pack - flap - happy 




L 


I 




tow - /ate - call 


T 




I 


rip - par - asked 




W 


w 




wake ■ always - when - quit 


K 




k 


frill - kick 




Y 


J 




yard • berry 


DT 




t 


buffer 




A.A1.A2 


e, el,e2( 


ei) 


tame - pa/I - make 


Z 




z 


zap - haze - pans 




E,E1 


i, il 




beef - be - even 


ZH 




I 


pleasure - azure 




1,11,12,13 


i.il, i2, 


i3 


p/t - /n - sw/m 


V 




V 


van - pave 




0,01,02 


o, ol, o2 




for - torn - bold 


THV 




b 


the - smooth - mother 


U,U1 


u, ul 




move - school - June 


J 




^ 


job - jazz - age 




AE.AE1 


ae, ae1 




dad - pla/d 


S 




s 


soup - ask - pass • 


;ity 


AH,AH1,AH2 


a, a1, a2 




top - father 


SH 




/ 


sheep - fish - acfior 




AW,AW1,AW2 


o, 01, 02 




call - paw 


F 




f 


fa/ce - cuff - phone 


laugh 


EH,EH1,EH3,EH3 


e, el, e2, 


ii 


ready - leg - said 


TH 




e 


thing - math 




ER 


& 




third - heard • chum - over 


CH 




t/ 


cheese ■ march - match 


UH,UH1,UH2,UH3 


a, aI, a2, 


3 


cop - random • around - under 


H 




h 


hoop - have 




00,001 
IU 


u, ul 
lju) 




took - put - good - could 
you - music 


M 




m 


mat - dim 




AY 


tei) 




jade - made - cla/m 


N 




n 


no - son 




Y1 


(Jul 




you - music 


Table 1: 


Phoneme- 


conversion 


table. Shown are the 


Votrax and IPA (Internationa 


/ Phonetic 


Alphabet) phonetic symbols and 


example 


words that show the 


pronunciation of each 


sound. 











176 February 1981 © BYTE Publications Inc 



Circle 113 on inquiry card. 



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Front Vowels 


Medial Vowels 


Back Vowels 




Mouth 


Base Vowels 


E 

1 

A 

EH 
AE 


ER 
UH 


U 

00 



AW 

AH 




Closed 

t 

Open 


Vowel 

Allophones 

(durational) 


E1 

11,12,13 

A1.A2 

EH1,EH2,EH3 

AE1 


UH1,UH2,UH3 


U1 

001 

01,02 

AW1.AW2 

AH1.AH2 




Closed 

f 

Open 


Vowel 

Allophones 

(sound) 


Y1 (short, constricted E1) 
AY (short, relaxed E1) 


IU (between 
the 001 
and U1) 




Closed 


Table 2: Vowel phonemes are categorized here according to their place of production within the human vocal tract. Durational 
vowel allophones have a number following their symbol which indicates their durational relationship to the base vowel. (The suf- 
fix 1 indicates the longest duration; 3 indicates the shortest duration.) The Votrax phonetic symbols are used here. 



Consonants 



Voiced 

B,D,G 

Z,ZH,V,THV,J 

M.N.NG 

R.L.W.Y 



Voiceless 

P,T,K,DT 
S,SH,F,TH,CH,H 



Group Name 

Stop Plosives 
Fricatives/Affricates 
Nasals 
Semivowels/Glides 



Table 3: Consonant phonemes are listed here according to their voicing quality and grouped according to the manner in which 
they are produced. Note that all vowels are classified as voiced phonemes. 



Phoneme 




Phoneme 




Sequence 


Usage 


Sequence 


Usage 


D-J 


" j" "-like sounds. 


S 


Completes the phonetic sequence of a 




Example: Judge = D-J-UH3-UH1-D-J 




word being pluralized only when the root 
word ends in a voiceless sound other than 


T-CH 


"ch"-like sounds. 




S or SH. 




Example: Church = T-CH-ER-R-T-CH 




Examples: plants = P-L-AE1-EH3-N-T-S 
shops = SH-AH1-UH3-P-S 


PAO 


A short pause between words for rhythm. 
Example: Copy this list = K-AH1-UH3-P- 




laughs = L-AE1-EH3-F-S 




Y-PA0-THV-I3-I2-S-L-I1-S-T 


D 


Completes the phonetic sequence of 




Also used to separate stop-plosive sounds 




a word with a past-tense suffix only 




like "k"and "t" when they occur in se- 




when the root word ends in a voiced 




quence. Example: Correct = K-02-R-EH2- 




sound or a T. 




K-PAO-T 




Examples: smiled = S-M-AH1-Y-UH3-L-D 
scored = S-K-01-02-R-D 


PA1 


The first and last phoneme in the com- 
pleted sequence, used for maintaining the 




wanted = W-AH1-UH3-N-T-I3-D 




articulation of the first and last sound in 


T 


Completes the phonetic sequence of a 




the sequence. Example: The sequence is 




word with a past-tense suffix only when 




complete = PA1-THV-UH3-UH3-S-E1-K- 




the root word ends in a voiceless sound 




W-EH1-N-T-S-PA0-I3-I3-Z-K-UH1-P-L-AY- 




other than T. 




Y-T-PA1 




Examples: typed = T-UH3-AH2-Y-P-T 

matched = M-AE1-EH3-T-CH-T 


Z 


Completes the phonetic sequence of 




washed = W-AW-SH-T 




a word being pluralized. Used only when 




missed = M-I3-I1-S-T 




the root word ends in a voiced sound, an 








S, or an SH. (See table 3 for a list of 








voiced sounds.) 








Examples: cans = K-AE1-AE1-N-Z 








balls = B-AW-L-Z 








goes = G-01-U1-Z 








ashes = AE1-EH3-SH-I3-Z 








buses = B-UH3-UH1-S-I3-Z 






Table 4: Since a number of phonetic sequences consistently produce intelligible 


speech, they can be classified as phonetic pattern 


rules. The most 


consistent patterns are shown here. Other phonetic 


patterns are 


more flexible, and many specific "sound effects" 


can be created 


through experimentation. 







178 February 1981 © BYTE Publications Inc 



SuperSoft's 

Gallery of CP/M Mas^erwbrks 





SUPER-M-LIST: A complete, easy to use mailing list program 
package. Allows for two names, two addresses, city, state, zip and 
a three digit code tield lor added flexibility. Super-M-List can sort 
on any field and produce mailing labels direct to printer or disk file 
for later printing or use by other programs. Super-M-List is the 
perfect companion to TFS. Handles 1981 Zip Codes! 
Requires: 48K CP/M 
Supplied with complete user manual: $75.00 manual alone: $10.00 

TFS-Text Formatting System: An extremely powerful formatter. 
More than 50 commands. Supports all major features including: 
• left & right margin justification • user defined macros 

■ dynamic insertion from disk file • underlining and backspace 
TFS lets you make multiple copies of any text. For example: Per- 
sonalized form letters complete with name, address & other inser- 
tions from a disk file. Text is not limited to the size of RAM making 
TFS perfect for reports or any big job. Text is entered using CP/M 
standard editor or most any CP/M compatible editor. 
Requires: 24K CP/M 

Supplied with extensive user manual: $85.00 manual alone: $20.00 
Source to TFS in 8080 assembler (can be assembled using stan- 
dard CP/M assembler) plus user manual: $250.00 



TEXT PROCESSING 




DIAGNOSTICS I: Easily the most comprehensive set of CP/M compatible 

system check-out programs ever assembled. 

Tests: 

• Memory • CPU (8080/8085/Z80J • Terminal • Disk • Printer 
To our knowledge the CPU test is the first of its kind anywhere. Diagnostics 
I can help you find problems before they become serious. A good set of 
diagnostic routines are a must in any program library. Minimal re- 
quirements: 32K CP/M. Supplied with complete user manual: $75.00 Manual 
alone: $15.00 



DIAGNOSTICS II: Includes all of Diagnostics I, plus: 

• Every test is "submif'-able 

• A complete Spinwriter/Diablo/Qume test has been added 
(Serial Interface only) 

• Output may be logged to disk 

• Expanded memory test 

• Expanded terminal test 
Expanded disk test 

Diagnostics II provides the next level in system maintenance. 

Requires: 32K CP/M 

Price: $100.00 Manual only: $15.00 



SYSTEM MAINTENANCE 




**** ** A ntnt , **■****** A ^JP 



'TINY' PASCAL II: We still call it 'Tiny- but it's bigger and better than ever! This is 
the famous Chung-Yuen 'Tiny' Pascal with more features added. Features include: 

• recursive procedures/functions • integer arithmetic • CASE 

• FOR (loop) • sequential disk I/O • 1 dimensional arrays 

• IF...THEN...ELSE • WHILE • PEAK & POKE 

• READ & WRITE • REPEAT...UNTIL • more 

"Tiny" Pascal is fast. Programs execute up to ten times faster than similar BASIC 
programs. SOURCE TOO! We still distribute source, in 'Tiny' Pascal, on each 
discette sold. You can even recompile the compiler, add features or just gain in- 
sight into compiler construction. 

Requires: 36K CP/M. Supplied with complete user manual and source on discette: 
$85.00. Manual alone: $10.00 

STACKWORK'S FORTH: A full, extended Forth interpreter/compiler produces 
COMPACT, ROMABLE code. As fast as compiled FORTRAN, as easy to use as in- 
teractive BASIC. 
SELF COMPILING: Includes every line of source code necessary to recompile 

itself. 
EXTENSIBLE: Add functions at will. 
Z80 or 8080 ASSEMBLER included. 
Single license, OEM licensing available. 
Please specify CPU type: Z80 or 8080 
Supplied with extensive user manual and tutorial: $175.00 
Documentation alone: $25.00 

SSS FORTRAN: The SSS FORTRAN compiler is fast, efficient, and complete 
(full 1966 ANSI standard with extensions). The RATFOR compiler compiles into 
FORTRAN allowing the user to write structured code while retaining the 
benefits of FORTRAN. The FORTRAN supports many advanced features not 
found in less complete implementations, including: complex arithmetic, 
character variables, and functions. Complete sequencial and random disk I/O 
are supported. SSS FORTRAN will compile up to 600 lines per minute 1 Recur- 
sive subroutines with static variables are supported. ROMable "COM files 
may be generated. SSS RATFOR allows the use of contemporary loop control 
and structured programming techniques. SSS RATFOR is similar to FORTRAN 
77 in that it supports such things as: 

• REPEAT...UNTIL • WHILE - IF.. THEN... ELSE 
SSS RATFOR is supplied with source code in FORTRAN and RATFOR. 
System Requirements & Prices: 

SSS FORTRAN requires a 32K CP/M system. 
SSS FORTRAN with RATFOR: $325.00 
SS FORTRAN alone: $250.00 

RATFOR alone: $100.00 

(Sold only with valid SSS FORTRAN license) 



VWWH 



PROGRAMMING LANGUAGE 



sj^^gg^g jB 




UTILITIES I: A collection of programs that you will find useful and 

maybe even necessary in your daily work (we did!). 

Includes: 

GREP: Searches files for a specified string 

SORT: In core sort of variable length records 

CMP: Compare two files for equality 

PRINT: Formatted listings to printer 

PG: Lists files to CRT a page at a time 

. . . plus more . . . 
Requires: 24K CP/M 
Supplied with manual on discette: $60.00 

UTILITIES II: Many new programs not available elsewhere. Includes these 
"file" utilities: 

DIFF: Source comparitor 

PR: Powerful multicolumn output formatter 

CAT: Concatenate files 

RPL: Substitute strings in files 

. . . plus more . . . 
Requires: 24K CP/M $60.00 
Supplied with manual on discette 



UTILITIES f" 




TERM: A complete intercommunications package for linking your com- 
puter to other computers. Link either to other CP/M computers or to large 
timesharing systems. TERM is comparable to other systems but costs 
less, delivers more and source is provided on discette! With TERM you 
can send and receive ASCII and Hex files (COM too, with included conver- 
tion program) with any other real time communication between users on 
separate systems as well as acting as timesharing terminal. 

• Engage/disengage printer • error checking and auto retry 

• terminal mode for timesharing between systems 

• conversational mode • send files • receive files 
Requires: 32K CP/M 

Supplied with user manual and 8080 source code: $150.00 
Manual alone: $15.00 



1 INTERCOMPUTER COMMUNICATIONS! 



* 


... j ;"-. ; ' --' j . -'■>.... ' r' :c ■ ' ■■" \Jf' 




ANALI2A: An amazingly accurate 


: I : 


.-.-. 


simulation of a session with a 




'■.-/ 


psychiatrist. Better than the famous 




:'\ 


"ELIZA" program. Enlightening as 


.V. 




well as fun. An excellent example of 


■.-.' 


: 


Artificial Intelligence. 
Requires: 48K CP/M, CBASIC2 






Cost: $35.00 


■-- 


P- 


j ENTERTAINMENT \ / 3 


£ 



^ 


■.:"-... ,; '- ; : ' ... %&* -: ... '','.:'" Z > 


/ 


'•)} 


ZB000CROSSASSEMBLER:Supports: 
full ZB000 syntax, segmented and 






unsegmented mode, full 32-bil 


-.-.- 


V. 


arithmetic, hex output, listing output. 


: : : 


*.v 


"downloader" 


SB 




Requires: 56K CP/M $500.00 
1 year maintenance $300.00 


':-.■ 


■*Yi 


manual alone $ 50.00 


■*'■ 


$ 


■ . : <-' : -| Z8000too! I ™ ■• ft 


* 



ENCODE/DECODE: A complete software security system for CP/M. 
Encode/Decode is a sophisticated coding program package which trans- 
forms data stored on disk into coded text which is completely unrecog- 
nizable. Encode/Decode supports multiple security levels and passwords 
A user defined combination (One billion possible) is used to code and 
decode a file. Uses are unlimited. Below are a few examples: 

• databases • payroll files ■ programs ■ tax records 

Encode/Decode is available in two versions: 

Encode/Decode I provides a level of security suitable for normal use 
Encode/Decode II provides enhanced security for the most demanding 
needs. 
Encode/Decode I: $50.00 Encode/Decode II: $100.00 manual alone: $1 500 



SOFTWARE SECURITY | 



On line "Help" system provided with every program package. 



SuperSoft 

First in Software Technology circle m on inquiry card. 



CP/M Formats: 8" soft sectored, 5" Northstar, 5" Micropo- 
lis Mod II, Vector MZ, Superbrain DD/QD 



All Orders and General Information: 

SUPERSOFT ASSOCIATES 

P.O. BOX 1628 

CHAMPAIGN, IL 61820 

(217) 359-2112 

Technical Hot Line: (217) 359-2691 

(answered only when technician Is available) 

CP/M REGISTERED TRADEMARK DIGITAL RESEARCH 



Circle 115 on inquiry card. 



the POWER 

Of Your HP-85 or Commodore Pet/CBM With TNWs IEEE-488 Bus 
System Building Blocks... 




TNWs RS-232SERIAL INTERFACES 



Connect your PET/CBM to any RS-232 Serial Printer, Piotter, 
Terminal. Modem, or other device: 



CRT 



TNW-1000 
TNW-2000 
TNW-232D 



ONECHANNEL 
OUTPUT ONLY 



ONECHANNEL 
INPUTANDOUTPUT 



TWO CHANNELS, INPUT & OUTPUT 
12 RS-232 CONTROL SIGNALS 



$129 
$229 
$369 



TURN YOUR PET INTO ATERMINAL 

Access Timesharing Systems and Bulletin Boards with TNWs Pterm 
Software and full service telephone modem: 



TNW-103 



AUTO ANSWER/AUTO DIAL 
USE WITH DAA 



$389 



Pterm also works with acoustical couplers and other modems interfaced 
to the PET with the TNW-2000 or TNW-232D. Electronic mail and TWX 
Terminal programs also available. All units are addressable IEEE-488 
devices, complete with power supply cabinet, full documentation and one 
year warranty. 

TNW CORPORATION 

3351 Hancock St. • San Diego, CA. , 92110 (714)225-1041 

TWX910-335-1194 

Visa/Mastercharge Welcome • Dealer inquiries invited 




Not for sale in any 
bookstore! Not avail- 
able at any price ! 
The new Consumer 
Information Catalog ! 

It's the free booklet 
that lists over 200 
helpful Federal pub- 
lications; more than 
half, free. On topics 
like home repairs. 
Money management 



fpflbS. Generai Services Administration 
180 February 1981 © BYTE Publications Inc 



Nutrition. Informa- 
tion that could help 
you to a better way 
of life. 

To get your free 
copy, just write : 

CONSUMER 

INFORMATION 

CENTER, 

DEPT E 

PUEBLO, COLORADO 

81009 



AE1-I3 



AH1-UH3 



Phoneme Sequence Usage 

AE1-EH3 The vowel sequence, for words requiring 

the AE sound, that creates smooth pro- 
nunciation transition from the vowel into 
the following consonant. Also used to 
create duration for the stressed syllable. 
Examples: admit = AE1-EH3-D-M-I1-I3-T 
dash = D-AE1-EH3-SH 

The vowel sequence for words requiring 
the AE sound followed by NG or another 
nasal sound. 
Example: hanger = H-AE1-I3-NG-ER 

The vowel sequence, for words requiring 
the AH sound, for smooth transition into 
other sounds. 
Examples: got = G-AH1-UH3-T 

father = F-AH1-UH3-THV-ER 

S-S Doubles the S phoneme when more dura- 

tion is desired, as at the end of a phrase 
or sentence. 
Examples: gas = G-AE1-EH3-S-S 

witness = W-I1-I2-T-N-I3-S-S 

D-J-J Doubles the fricative portion of the "J" 

sound sequence for emphasis. 
Examples: Germany = D-J-J-ER-R-M-I3-N-Y 
large = L-AH1-UH3-R-D-J-J 

Table 5: In voice synthesis, it is often desirable to lengthen 
or shorten a vowel or consonant sound at the end of a 
syllable, word, phrase, or sentence. Shown here are several 
of the most common "tricks" for creating such effects. 



Text continued from page 174: 

lines might produce an awkward, if not unintelligible, 
pronunciation of the word being translated. The pronun- 
ciation guidelines from any phonetic symbol system 
(IP A, Webster's Dictionary, Thorndike's Dictionary) can 
be used to establish a basic synthesized phoneme se- 
quence, but listening is the final step used to determine 
the selections for a refined phoneme sequence (see text- 
box, "Programming Phoneme Voice Synthesizers," on 
page 176). 

For the purposes of this article, all phonetic sequences 
are presented utilizing the Votrax Phonetic Symbol Sys- 
tem. This system is used because it utilizes characters that 
are" found on a standard computer terminal, as well as 
those needed for translation. 

Phonemes 

The sixty-four synthetic phonemes produced by a 
Votrax speech synthesizer are used here as the base syn- 
thetic-phoneme reference. The phonetic symbols repre- 
senting these sounds and example words are listed in 
table 1 on page 176. There are twenty-five different con- 
sonant sounds, thirty-six basic vowel and vowel-allo- 
phone sounds, and two pause phonemes. The sixty- 
fourth phoneme is called a zero-decode command pho- 
neme. It emits no sound, but can be used as a short inter- 
ruption. When you select the appropriate synthetic 
sounds and place them in a specific sequence, the speech 
synthesizer can produce any word in the English language 
(as well as many other languages). 

Vocabulary Storage 

Vocabulary storage requirements are dependent on the 



HOT WINTER PRICES ON PERSONAL 
COMPUTERS AND COMPONENTS. 



Look at this! 






Ohio Scientific 
Superboard II 

$299 



• It's the first complete computer 
system on a board. 

• Superboard II uses the ultra 
powerful 6502 Microprocessor 

• 8K Microsoft BASIC-in-ROM 

• 4K static RAM on board, 
expandable to 8K 

• Full 53-key keyboard, with upper 
and lower case. Plus user 
expandability. 

• Video interface and audio 
cassette interface. 

The Ohio Scientific Superboard II at 
$299 — in today's economy — has 
got to be the best buy by far. It will 
entertain you with spectacular 
graphics made possible by its ultra 
high resolution graphics and super 
fast BASIC. It will help you in school 
or industry, as an ultra powerful 
scientific calculator. Advanced 
scientific functions and a built-in 
"immediate" mode allow you to 
solve complex problems without 
programming. 

The Superboard II can be 
expanded economically, for business 
uses, or to remotely control your 
home appliances and security. Even 
communicate with other computers. 

Read what's been written 
about Superboard II: 

"We heartily recommend Super- 
board II for the beginner who wants 
to get into microcomputers with a 
minimum cost. A real computer 
with full expandability." 
— POPULAR ELECTRONICS, MARCH 1979 

"The Superboard II is an excellent 
choice for the personal computer 
enthusiast on a budget." 

-BYTE, MAY 1979 



Look at these easy hardware prices: 

610 Board For use with Superboard II and Challenger 1 P. 

BK static RAM. Expandable to 24K or 32K system total. 

Accepts up to two mini-floppy disk drives. Requires + 5V 

@4.5 amps. S 298 

Mini-Floppy Disk Drive Includes Ohio Scientific's PICO DOS 

software and connector cable. Compatible with 610 

expander board. Requires + 1 2V @1 .5 amps and + 5V @ 

0.7 amps. [Power supply S. cabinet not included.] 299 

630 Board Contact us for important details. 229 

AC-3P 12" combination black and white TV/video monitor. 159 

4KP 4K RAM chip set. 79 

P8-005 5V 4.5 amp power supply for Superboard II. 35 

P8-003 1 2V power supply for mini-floppies. 29 

CS-600 Metal case for Superboard II, 610 and 630 board 

and two power supplies. [While stock lasts.] 49 

CS-900B Metal case for single floppy disk drive and power 

supply. [While stock lasts.] 49 

AC-12P Wireless remote control system. Includes control 
console, two lamp modules and two appliance modules, for 
use with 630 board. 175 

AC-17P Home security system. Includes console, fire 

detector, window protection devices and door unit for use 

with 630 board. 249 

C1P Sams C1P Service manual 8 

C4P Sams C4P Service manual 16 

C3 Sams Challenger III manual 40 

Ohio Scientific and independent suppliers offer hundreds of programs for the 
Superboard II, in cassette and mini-floppy form. 



Freight Policies All orders of$100ormoreare 

shipped freight prepaid. Orders of less than SI 00 please add 
$4.00 to cover shipping costs. Ohio residents add 5.5% Sales Tax. 



ri Hours: Call Monday thru Friday. 
B;00 AM to 5:00 PM E.O.T. 
TOLL FREE: 1-800-331-5805 



Guaranteed Shipment 

Cleveland Consumer Computers S. Components 
guarantees shipment of computer systems 
within 48 hours upon receipt of your order. 
Our failure to ship within 48 hours 
entitles you to 835 of software, FREE. 



TO Order: Or to get our free catalog CALL 1-800-321-5805 TOLL FREE. Charge your 

order to your VISA or MASTER CHARGE account. Ohio residents call: [216] 464-8047. 
Or write, including your check or money order, to the address listed below. 



I 

I 
I 
I 
I 

I 
I 
I 

I 



CLEVELAND CONSUMER 
U| COMPUTERS & COMPONENTS 

| P.O. Box 46627 

i Cleveland, Ohio 44146 

■ BB1BB1BH ■■■■■■■■■■■■■■■■■■■ BB1 ■"■■"■■"■ BB1 BB1 ■ 
flhrlan Cnnmi Cleveland consumer p.o. Box4eg27 

Wl UCI rill Ilia COMPUTERS B COMPONENTS Cleveland, Ohio 44146 

□ Superboard II $299. □ 630 Board $299. 

□ 610 Board $298. □ AC-3P 12" B/W Monitor $159. 

□ Mini-Floppy Disk Drive $299. □ C1 P Sams Manual $8. 
[Attach separate sheet for other items.] 

NAME 

ADDRESS: 

CITY: 

PHONE: 



. STATE: 



.ZIP: 



Payment by: VISA 

Credit Card Account #_ 
Expires 



MASTER CHARGE . 



MONEY ORDER 



Interbank #[Master Charge] 



TOTAL CHARGED OR ENCLOSED $_ 



. [Ohio Residents add 5.5% Sales Tax) 



Orders of less then $1 00. please add $4.00 to cover shipping costs. 

All orders shipped insured UPS unless otherwise requested. FOB Cleveland, Ohio. 



Circle 117 on inquiry card. 



BYTE February 1981 



181 



FOR THE APPLE 




Please send: IJ Complete System S495.00 
□ User's Manual only S35.00 
D Detailed information 



Name _ 
Address _ 

City 

State 



Zip- 



applied analytics incorporated 
5406 Roblee Dr., Upper Marlboro. MO 20870 



Listing 1: An example assembly -language program designed to store a permanent 
vocabulary for voice synthesis in a read-only memory. The program generates a table 
of words which the user has entered and stores them sequentially in memory. It then 
produces a look-up table with entries that point to the corresponding word in the word- 
storage table. 



00004 
00005 
00006 

00008 

00010 1000 > 

00011 1000 00200820> 

00012 1004 0D201220> 

00013 1008 17201B20> 

00014 100C 20202420> 

00015 1010 29202E20> 

00016 1014 34203B2O 

00018 
00019 

00022 
00023 
00024 
00025 

00027 

00028 2000 

00028 2004 

00029 2008 

00029 200C 

00030 200B 

00030 2011 

00031 2012 

00031 2016 

00032 2017 

00033 201B 

00033 201F 

00034 2020 

00035 2024 

00035 2028 

00036 2029 

00036 202B 

00037 202E 

00037 2032 

00038 2034 

00038 2038 

00039 203B 

00041 
00042 
00043 
00045 

00047 0000 

00048 0039 

00049 003B 

00050 002A 

00051 0002 

00052 0004 

00053 0005 

00054 0033 

00055 0035 

00056 002F 

00057 0006 

00058 0009 

00059 0023 

00060 0028 

00061 OOOB 

00062 OOOC 

00063 OOOB 

00064 OOOE 

00065 OOOF 

00066 0010 

00067 0012 

00068 0013 

00069 0014 

00070 0015 

00071 0038 

00072 0016 

00073 0026 

00074 0019 

00075 001A 

00076 0030 
00077 



2000 5 

39350B30 

13333513 

0212002A 

OB 

0B0C0F15 

1A 

04092313 

OB 

06120526 

0C333506 

14 

0E281515 

13143B38 

10 

143B3526 

OD 

19281515 

1A2F 

1639350C 

192815 

00 



THIS DEMONSTRATES HOU AN ASSEMBLER 
CAN PACK A UORB TABLE ANB GENERATE 
THE APPROPRIATE UORB LOOK-UP TABLE 

THIS IS THE LOOK-UP TABLE 



ORG 1000H 


UORB 


ACCESS, BREAK 


UORB 


CLOSE. BISK 


UORD 


FREE. LEFT 


WORD 


NEU.STOP 


UORD 


TIME. USER 


UORB 


VALUE, XXX 



THIS TABLE UILL CONTINUE FOR AS MANY 
ENTRIES AS DESIRED OR MEMORY ALLOUS 

THIS IS THE UORD STORAGE TABLE, IT CAN BE 
PLACEB UHERE YOU DESIRE. UORDS APPEAR IN THE 
ABOVE ORDER INORDER TO USE THE START OP THE 
NEXT UORD AS THE STOP FLAG 01 THE CURRENT UORD 

ORG 2000H 
ACCESS BYTE AE1 , EH3. K.PAO .S . »EH1 ,EH3 . S ■ 

BREAK BYTE B . . R . , Al . A Y,K 

CLOSE BYTE K , L . ,01 , Ul , Z . 



DISK BYTE D, ,I1,I3,S,,K 



FREE BYTE F,R,,E1,Y 
LEFT BYTE L . , EH1 , EH3, F »T 



NEU BYTE N,IU,U1,U1 
STOP BYTE S,,T,AH1,UH3,P. 



TIME BYTE T , AH1 , EH3 , Y , M . 



USER BYTE Yl , IU.U1.U1 , Z . , ER 



VALUE BYTE V » AE1 ,EH3. L . , Yl . IU . Ul 



XXX 



BYTE 



NOTICE! THIS SCHEME DOESNT CARE HON MANY 
BYTES ARE ALLOCATED TO EACH UORD. THERE ARE 
MANY VARIATIONS ON THIS SCHEME. 
PARTIAL PHONEME EUUATES BELOU 



Al 

AE1 

AH1 

AY 

B. 

D. 

El 

EH1 

EH3 

ER 

F 

II 

13 

IU 

K 

L. 

M. 

N 

01 

P. 

R. 

S. 

T 

Ul 

UH3 

V 

Y 

Yl 

Z. 

PAO 




57 
59 
42 



EQU 
EQU 
EQU 
EQU 
EQU 2 
EQU 4 
EQU 5 
EQU 51 
EQU 53 
EQU 47 
EQU 6 
EQU 9 
EQU 35 
EQU 40 
EQU 11 
EQU 12 
EQU 13 
EQU 14 
EQU 
EQU 
EQU 18 
EQU 19 
EQU 
EQU 
EQU 
EQU 
EQU 38 
EQU 25 
EQU 26 
EQU 48 
END 



15 
16 



>0 
21 

56 
on 



182 February 1981 © BYTE Publications Inc 




32K Board Pictured Above 



Why Not the Best? 

From The Dynamic RAM Company. 



2MHz 


4MHz 


16K— $249 


$259 


32K— $375 


$395 


48K— $500 


$530 


64K— $625 


$665 



We have now been shipping 
our 2MHz dynamic RAM boards 
for over two years. Hundreds of 
4MHz boards have been going 
out every month since early 
1979. Our reliability is proven in 
the thousands of systems which 
contain our board. Many quality- 
minded systems houses across 
the country and overseas are 
using our boards for their 
equipment. 

Our prices still beat all. 
Despite rising 16K memory chip 
prices (at least from reputable 
suppliers), Central Data continues 
to give you the best buy in 
memory today. Nobody offers a 
board with a capacity of 64K, 
assembled, tested, and guaranteed 
for a full year at the price we do. 

Circle 118 on inquiry card. 



Deselect around PROMs. Our 

boards have the important deselect 
feature which lets you overlap any 
fixed memory in your system with 
no interference. 

Our features make the board 
easily used and expanded. You 
address our boards on 1 6K 
boundaries with mini-jumps (small 
shorting plugs that slide over wire- 
wrap pins) near the top of the 
board for easy access. If you want 
to expand your board after you 
have purchased it, all that you 
need to do is add memory. We 
can supply you with expansion 
packages ($1 50-2MHz, 
$160-4MHz) which include eight 
RAMs that you can depend on as 
well as two mini-jumps for 
addressing. And of course, our 
board never generates wait states. 

Low power consumption keeps 
your computer running cool and 
reliable. The total power 
consumption of our 1 6K board is 
typically less than 4 watts ( + 8V @ 
300ma, + 1 6V @ 1 50ma and 



- 1 6V @ 20ma). Boards with 
additional memory typically 
increase power consumption only 
1 watt per 16K! 

Standard S-100 Interface. Our 
board is designed to interface with 
any standard S-100 CPU. All of 
the timing of the board is 
independent of the processor chip, 
and the board is set up for 
different processors by changing 
two plugs on the board. 

Call or write us today. That will 
guarantee a fast response with 
more information on the board. Or 
make an order — you'll probably 
have the board in two weeks! If 
you're interested, also ask for a 
catalog on our Z8000 16-bit 
processor board designed for the 
MULTIBUS. All of these products 
are available to your local dealer, 
also. 

Central Data Corporation, 713 
Edgebrook Drive, PO Box 2530, 
Station A, Champaign, IL 61820. 
(217) 359-8010 



Central Data 



BYTE February 1981 



183 



Your vehicle for com 

The Challenger 8P DF. 



The general purpose microcomputer 
was first introduced as a computer 
for hobbyists and experimenters. 
However, as the industry has grown, 
microcomputers have become 
specialized for personal use or for 
small business use. There is virtually 
no computer for the serious experi- 
menter with one important exception, 
the Ohio Scientific Challenger 8 P. 

The C8P is unique in that it incor- 
porates the features of state-of-the- 
art personal computers, with the 
memory and disk storage capacity 
of business computers, along with 
the "mainframe" bus architecture 
and open ended expansion capability 
of industrial control computers. 

Personal Computer 
Features 

The C8PDF's specs 
beat all personal 
computers hands 
down. It executes 
instructions two 
to three times 
faster, and 
displays more 
alphabetic 
characters 
on its screen 
than other 



models. It has upper and lower case 
and graphics in 16 colors. The C8P's 
standard I/O capabilities are far 
more extensive than any other com- 
puter, with joystick and keypad inter- 
faces, sound output, an 8-bit D/A 
converter, 16 parallel I/O lines, 
modem and printer interfaces, AC 
remote control and security monitor 
interfaces and a universal acces- 
sory port that accepts a prom blaster, 
12-bit analog I/O module, solderless 
prototyping board and more. 

Ohio Scientific offers a large library 
of personal applications programs, 
including exciting action games 
such as Invaders and Star Trek, 
sports simulations, games of logic 



and educational games, personal 
applications such as biorhythms, 
calorie counter, home programs 
such as checking and savings 
account balancers and a home 
budgeter just to name a few. A new 
Plot BASIC makes elaborate anima- 
tions easy, and music composition 
program allows you to play complex 
multi-part music through the com- 
puters DAC. 

At the systems level the machine 
comes standard with OS-65D, an ad- 
vanced disk operating system with 
Microsoft BASIC and an interactive 
Assembler Editor. Optional software 
includes UCSD PASCAL and 
FORTRAN and an Information 
Management System (OS-MDMS). 
Dozens of independent software 
suppliers now also offer personal 
programs for the C8P. 




I 





puter explorations. 



Business Computer Features 

The C8P DF utilizes dual 8" floppy 
disk drives which store up to eight 
times as much information as per- 
sonal computer mini-floppies, and 
an available double-sided option 
expands capacity to 1.2 megabytes 
of on-line storage. The C8P DF is 
compatible with Ohio Scientif ic's 
business computer software, in- 
cluding OS-65U an advanced oper- 
ating system, and an Information 
Management System (OS-DMS) with 
supplementary inventory, account- 
ing, A/R-A/P, payroll, purchasing, 
estimation, educational grading and 
financial modeling packages. The 
system also supports word process- 
ing (WP-3) and a fully integrated 
small business accounting system 
(OS-AMCAP V1.6). The C8P DF's 
standard modem and printer ports 
accept high-speed matrix printers 
and word-processing printers directly. 

Home Control and 
Industrial Control 

The C8P DF has the most advanced 
home monitoring and control capa- 
bilities ever offered in a computer 
system. It incorporates a real time 
clock and a unique FOREGROUND/ 
BACKGROUND operating system 
which allows the computer to 
function with normal BASIC pro- 
grams, at the same time it is 
monitoring external devices. 
The C8P DF comes standard 
with an AC remote control 

interface, which 



allows it to control a wide range of 
AC appliances and lights remotely, 
without wiring, and an interface for 
home security systems which moni- 
tors fire, intrusion, car theft, water 
levels and freezer temperature, all 
without messy wiring. In addition, 
the C8P DF can accept Ohio Scien- 
tific's Votrax voice I/O board and/or 
Ohio Scientific's new universal 
telephone interface (UTI). The tele- 
phone interface connects the com- 
puter to any telephone line. The 
computer system is able to answer 
calls, initiate calls and communicate 
via touch-tone signals, voice outpu t 
or 300 baud modem signals. It can 
accept and decode touch-tone 
signals, 300 baud modem signals 
and record incoming voice 
messages. These features collec- 
tively give the C8P DF capabilities to 
monitor and control home functions 
with almost human-like capabilities. 

For process control applications, a 
battery back up calendar clock with 
automatic computer restart capabili- 
ties is available. Ohio Scientific's 
unique accessory ports allow the 
connection of a nearly unlimited 
number of 48 line parallel I/O cards 
and 12-bit high speed instrumenta- 
tion quality analog I/O modules to 
the computer by inexpensive 16-pin 
ribbon cables. 

Exploring New Frontiers 

Ohio Scientific's vocalizer software 
processes normal BASIC print state- 
ments with conventional spellings 
and speaks them clearly in real-time 




on computers equipped with the UTI 
(CA-15B or CA-14A). This voice out- 
put capability, combined with the 
C8P's remote control, remote sens- 
ing, telephone interface capabilities 
and reasonable cost open up new 
frontiers for computer applications. 

Documentation 

The C8P DF is not a beginner's com- 
puter and doesn't come with begin- 
ner's documentation. However, Ohio 
Scientific does offer detailed 
documentation on the computer 
which is meaningful for experts, 
including a Howard Sams produced 
hardware service manual that in- 
cludes detailed block diagrams, 
schematics, parts placement dia- 
grams and parts lists. Ohio Scientific 
is now also offering fully 
documented Source Code in 
machine readable form for OS-65D, 
the Challenger 8P's operating 
system allowing experimenters and 
industrial users to customize the 
system to their specific applications. 

What's Next? 

Ohio Scientific is working on a 
speech recognizer to complement 
the UTI system, with a several hun- 
dred word vocabulary. The company 
is also developing an 8 megabyte 
low-cost, add-on hard disk for use in 
conjunction with natural language 
parsing to further advance the state- 
of-the-art in small computers. The 
modular bus architecture of the C8P 
assures system owners of being 
able to make use of these new 
developments as they become 
available just as the owner of a 1976 
vintage Challenger can directly plug 
in voice output, the UTI and other 
current state-of-the-art OSI 
products. 

The C8P DF with dual 8" floppies, 
BASIC and two operating systems 
costs about $3000, only slightly 
more than you would pay for a dual 
mini-floppy equipped personal com- 
puter with only a fraction of the 
capabilities of the C8R 

For more information and the 
name of the dealer nearest you, 
call 1-800-321-6850 toll free. 



1333 SOUTH CHILLICOTHE ROAD 
AURORA, OH 44202 • [21 6] 831 -5600 



Circle 155 on inquiry card. 




Listing 2: A driver program in BASIC which accesses the vo- 
cabulary as stored by the program shown in listing 1. The end of 
a word is detected by the starting address of the adjacent word 
in the table. 



Photo 5: A communicator for the verbally impaired. The 
Phonic Mirror HandiVoice HC-110 is a battery-operated speech 
synthesizer controlled by a microprocessor. The user can select 
from its 500 word/phrase vocabulary by touching the keypad. 




Photo 6: The Phonic Mirror HandiVoice HC-120 is an ad- 
vanced version of the voice synthesizer shown in photo 5. It has 
a 1000 word/phrase vocabulary selected by entering a 3-digit 
numeric code. Paralyzed users can operate the unit through the 
use of a paddle switch and a scroll mode. 




100 


' 


SF'EECH OUTPUT SUE:ROUTINE 


IN 


BASIC 


110 




PHONEMES ARE SELECTED FROM 


THE WORD 


120 




POINTED TO BY WNZ 






130 










140 


X - 


1000H + 2 » HN7. 


: 


' CALCULATE LOOK-UP ADDRESS 


lr-io 


V = 


F'EEK(X) + 256 * FEEKIX+1) 


; 


' LOOK-UP WORD START 


160 


z - 


PEEK<X+2> + 256 » PEEKCX+3) 


: 


1 LOOK-UP NEXT WORD START 


17 


F R 


X = Y TO Z-l 


: 


' SET UP LOOP ITERATIONS 


mo 


OUT 


SPEECH, PEEK(X) ! NEXTX 


j 


' OUTPUT A PHONEME 


190 


RETURN 


: 


' EXIT 



Photo 7: Talking typewriters for use by the verbally impaired. 
The units, which use phonemes, have a virtually unlimited 
vocabulary. 



number of words in the vocabulary and the number of 
bits in a phoneme-command word. For example, a vo- 
cabulary of 100 words using a 6- to 8-bit command word 
to represent each phoneme will require 600 bytes of stor- 
age. A 1000-word vocabulary will require 6000 bytes of 
storage. A 12-bit command word will require 900 to 1200 
bytes for a 100-word vocabulary and 9000 to 12,000 
bytes for a 1000-word vocabulary (depending on the 
packing techniques). 

When using a phoneme synthesizer with a 6-bit com- 
mand word and a high-level computer language that 
allows literal strings to be assigned to a variable, vocabu- 
lary storage can be embedded within the program state- 
ments by using ASCII strings. This is because a 6-bit 
command word has only sixty-four possible commands, 
where there are at least 64 printable ASCII characters. A 
word or phrase is assigned to a string variable immediate- 
ly before being sent to a speech-output routine. This 
routine pulls characters out of the string variable one at a 
time and sends them to the synthesizer. This technique is 
suitable for small vocabulary requirements. With large 
vocabularies, there tends to be word duplication because 
the storage unit is a sentence or phrase. 

A technique better suited for handling large word bases 
is the assignment of the phoneme string for a single word 
to a subscripted string variable. This avoids the word 
duplication experienced by the previous technique and 
saves memory (provided that the language stores char- 
acter strings with no wasted space). To generate a sen- 
tence using this technique, a sequence of variable sub- 
script numbers is passed to a routine which calls up the 
indicated variables. Phoneme strings are then removed 
from the variable and sent to the synthesizer. 

For permanent vocabularies stored in ROM (read-only 
memory) or loaded into programmable memory from a 
disk file, a word-address look-up scheme works well. 
This is done by generating a table of words stored se- 
quentially in a portion of the memory. You then produce 
a look-up table whose entries point to a word in the 
word-storage table. The number of the look-up-table en- 
try corresponds to the number assigned to the word (eg: 
the fifth entry in the look-up table will point to the fifth 
word in the word table). These tables can be generated 
easily (see listing 1). Sentences are called out in the same 
fashion as the previous scheme. 

The assembler scheme works well with any size pho- 
neme-command word, since it does not care how many 
bits are used to represent a phoneme. However, the 
driver program must know whether to pull 1, 1 Vz, or 2 
bytes per phoneme. Listing 2 shows a driver program in 
BASIC to access the vocabulary in listing 1. Note that the 



186 February 1981 © BYTE Publications Inc 



end of a word is detected by the starting address of the 
adjacent word in the table. 

Applications 

In the field of computer technology alone, there is 
tremendous potential for the use of speech output. 
Through voice synthesis, applications can expand into 
areas formerly closed. These are areas where a person 
must interact with a computer, but where visual output is 
inappropriate, unavailable, or ineffective. 

Currently, a blind person who wishes to use a com- 
puter must rely on a sighted person to relay information 
from a video display or printer. To eliminate this depen- 
dency, a terminal for the blind can be built to incorporate 
voice synthesis. Several such terminals are beginning to 
appear on the market. 

Another situation where speech output is desirable is a 
warehousing/dispatching system. It is not often cost- 
effective to place terminals around a large warehouse to 
list pending tasks. A better method is speech output from 
a computer connected to a radio link, which dispatches a 
worker carrying a pocket receiver /transmitter. Similar 
systems are in use or being developed today. 

Another area where computers are presently ineffec- 
tive is in interfacing with the nonreading population. 
Such is the case when the users are preschool children or 
nonreading adults. They are the prime candidates for us- 
ing CAI (computer-aided instruction) as a supplement to 
their education. Applications such as computerized test- 
ing and evaluation of children would invite advance- 
ments in the educational field if a speech-output channel 
was used. 

Synthetic speech applications are not limited to merely 
the computer peripherals mentioned. When used with a 
small, dedicated microcomputer or digital controller, a 
stand-alone device can be produced. Such is the case with 
a reading machine for the blind. 

A second type of stand-alone speech system is a com- 
municator for the verbally impaired. A battery-operated 
microcomputer system and a speech synthesizer can pro- 
vide a voice for individuals stricken with neurological or 
physical disorders which impair the human speech me- 
chanism (see photos 5 and 6). 

Other applications for voice synthesis are in the area of 
entertainment electronics. Talking card games, chess 
games, and video games are beginning to use voice syn- 
thesis. Many of these applications are made possible by 
LSI (large-scale integration) circuits such as the Votrax 
SC01 single-chip voice synthesizer. 

The interface of man-to-machine will provide a chal- 
lenge for the 1980s. Speech synthesis will play an impor- 
tant role in the future of computer technology. ■ 



Editor's Note: One of the first voice-synthesis products for 
consumers was Texas Instruments Speak & Spell, which uses 
a ten-stage lattice filter to simulate the human vocal tract. In 
the fall of 1980, as part of the continuing trend toward in- 
tegrating voice synthesis into everyday products, MB Elec- 
tronics (a subsidiary of Milton-Bradley) introduced an elec- 
tronic game called "Milton." The game is controlled by a 
Texas Instruments TMS-1000-series 4-bit microprocessor and 
utilizes a custom voice-synthesis integrated cii --•<( designed 
by MB engineers.... SM 



The time has come for computers 
to talk and listen 




Introducing COGNIVOX series VIO, 
the affordable voice I/O peripherals 



If you have a 

PET - TRS-80 - APPLE II 
AIM 65 - SORCERER 

or any Z-80 CPU based system with at least 16K of RAM, COGNIVOXwill 
add a whole new dimension to your computer. 

Imagine being able to use your voice for entry of commands and data 
and then listen to the computer talk back to you 1 This exciting possibility 
has now become a reality at a very affordable price. 

COGNIVOX, series VIO, is a family of voice input and output peripherals 
especially designed for personal computers that are easy to use and have 
excellent software support. You need only plug in COGNIVOX, load one of 
the programs provided and you will be able to have a voiceencounterwith 
your computer! 

COGNIVOX can be trained to recognize words or short phrases from a 
vocabulary of up to 32 entries of your choice, with an accuracy of up to 
98%. The voice response vocabulary can also have up to 32 entries 
chosen by the user. COGNIVOX requires that your computer has at least 
16K of RAM. If it has less memory or if you are only interested in 
recognition, ask us about our SR-100 series of voice input peripherals. 

COGNIVOX comes complete with microphone, power supply, (as 
required), built-in amplifier/speaker and extensive user manual. What 
makes COGNIVOX truly unique, though, is the soltware that comes with it 
on cassette. Some of the programs included are: DIALOG, a programthat 
lets you conduct a dialog with your computer (or translate from one 
language to the other); VDUMP, a vocal memory dump that reads the 
memory contents out loud; VOTH, a voice operated talking board game 
and VOICETRAP, a voice operated video game. 

Adding voice I/O to your own programs can be done very easily too. All 
that is needed to have your computer recognize a word or say a word is a 
single USR statement in BASIC. No machine language programming is 
necessary. 

With all these features, you'd expect COGNIVOX to cost a small fortune 
(after all, even talking chess games sell for over S300), yet it only costs 
$149 (add S4.50 for shipping in the U.S.. 10% of order overseas. CA res, 
add 6% tax) This low price has been made possible by innovative 
hardware and a technological breakthrough in recognition algorithm 
design that uses powerful non-linear pattern matching techniques and 
adaptive learning. 

COGNIVOX is simply the most fun, most exotic peripheral you can buy 
for your computer. Write or call (805) 685-1854 for more it, motion, 
giving us the make and model of your computer. Or better yet, order a 
COGNIVOX today and bring your computer to life. 



VOICETEK 



Dept B, P.O. Box 388 
Goleta, CA 93116 



Circle 119 on inquiry card. 



February 1981 © BYTE Publications Inc 187 



Circle 121 on inquiry card. 



REMOTE I/O 



■* ~* l *'WWP B 'MBMi 




Control AND monitor remote devices 
Real time clock/calendar included 

• An AC carrier communications I/O interface for the APPLE II* 
computer. Output communications operate up to 256 BSR System 
X-10* control modules. Input communications come from the X-10 
command console, and temperature and security input modules, 
soon to be available from Intelligent Control Systems, Inc. 

• Software routines are provided to handle the AC I/O, to set, 
read , and display the real time clock , and a background schedule 
control program. 4 selectable interrupt rates allow machine 
language programs to run simultaneously with other programs. 

• Real time clock provides sec, min, hour, date, day of week, mo, 
and year. Rechargable battery runs clock when APPLE is off. 

• Trademarks-APPLE II: Apple Computer Inc . , System X-10 :BSR Ltd . 
SEE YOUR APPLE DEALER FOR A DEMONSTRATION ... $185 Sugg . retail 

Intelligent Control Systems, Inc. 

POBOX 14571«MPLS,MN 5541 4« (612) 699-4342 



MICROSTAT 
NOW AVAILABLE FOR CP/M* 

MICROSTAT, the most powerful statistics package available 
for microcomputers, is completely file-oriented with a power- 
ful Data Management Subsystem (OMS) that allows you to 
edit, delete, augment, sort, rank-order, lag and transform (11 
transformations, including linear, exponential and log) existing 
data into new data. After a file is created with OMS, Microstat 
provides statistical analysis in the following general areas: 
Descriptive Statistics (mean, sample, and population S.D., 
variance, etc.). Frequency Distributions (grouped or individ- 
ual). Hypothesis Testing (mean or proportion). Correlation and 
Regression Analysis (with support statistics). Non-parametric 
Tests (Kolmogorov-Smirnov, Wilcoxon, etc.). Probability Dis- 
tributions (8 of them), Crosstabs and Chi-square, ANOVA (one 
and two way). Factorials, Combinations and Permutations, plus 
other unique and useful features, 

MICROSTAT requires 48K, Microsoft Basic-80 with CPIM 
and is sent on a single-density 8" Disk. It is also available on 
5" diskettes for North Star DOS and Basic (32K and two 
drives recommended), specify which when ordering. The 
price for Microstat is $250.00. The user's manual is $15.00 
and includes sample data and printouts. We have other 
business and educational software, call or write: 



ECOSOFT 



[master charge] 



P.O. Box 68602 
Indianapolis, IN 46268 
V (317)283-8883 

CP/M is a registered trade mark of Digital Research. 



Technical Forum 



Nonlinearities in 
Illumination 

Christopher Terry, 324 E 35th St, New York NY 10016 

I certainly do not wish to be hastily critical of an 
excellently documented and very interesting project. 
However, my points may help constructors to carry their 
experiments with computer-controlled light dimmers a 
bit further and to avoid disappointment with the results. 

The dimmer, as described in John Gibson's "A Com- 
puter-Controlled Light Dimmer" (January 1980 BYTE, 
page 56), will certainly fade a lamp from blackout to full 
brightness or vice versa. However, it is important to 
realize that a smooth, steady fade cannot be obtained by 
incrementing the delay count in equal steps throughout 
the fade time. Linear change of this kind is an analog of 
the steady motion of a dimmer slide, whose scale is nor- 
mally calibrated from to 10 in equal divisions. On the 
other hand, the response characteristics of the digital 
dimmer, of incandescent lamps, and of the eye itself, are 
all highly nonlinear. 

Figure 1 shows the curve of light output (expressed as a 
percentage of maximum light output in lumens) versus 
voltage applied to a lamp (expressed as a percentage of 
the rated, normal operating voltage). Data for this curve 
was taken from the Sylvania GTE Lighting Handbook 



180 


- 




1- 160 












a. 






t- 






o 14 ° 


- 




H 






I 






IS 120 


- 




_l 






D 






£ 100 










< 






a. 






u- 80 


- / 




O 






1- 






z 60 


/ 










u 






rr 






w 40 


r- ^r 










20 


1 I- 1 1 





20 40 60 80 

PERCENT OF RATED LAMP VOLTAGE 



100 



120 



Figure 1: The nonlinear response of light output versus the 
voltage applied to an incandescent lamp. Although the curve is 
almost linear above the 60% illumination point, an incandes- 
cent bulb can require as much as 40% of rated voltage to il- 
luminate at all. Note that driving lamps with higher-than-rated 
voltage will reduce life drastically. 



188 February 19B1 © BYTE Publications Inc 



Circle 1 22 on inquiry card. 



One Stop 
Shopping. 




New CPU Card 
Completes the 
Package. 

Now Tarbell offers a Z-80 S-100 CPU/IO board that 
rounds out its product line. Along with the single or 
double density floppy interface, the 32K memory card 
and the S-100 bus in the cabinet, this new CPU board 
means that Tarbell now offers everything needed to 
build a system. Just add a CRT and printer, and you're 
in business. Tarbell is now your one-stop shopping 
source. 

One of the outstanding features of this new CPU board 
is memory-management hardware that allows dynamic 
mapping of logical to 1 Megabyte of physical memory in 
4K blocks. Moreover, the CPU board is especially 



Service 



designed to make it easier to implement multiuser 
operating systems, such as MP/M™ from Digital 
Research. It can run at 2 or 4Mhz, jumper selectable. It 
has two RS-232 Serial Ports (one for printer and one for 
CRT), with full handshaking capability. 

One of its additional important features is a crystal- 
controlled programmable timer, which can be used for 
time-of-day clock and multi-tasking operations. 
Programmable priority masked vectored interrupt 
hardware is another useful feature. 

In addition to all the features of the new CPU card, the 
double density floppy interface has DMA which makes 
the multi-tasking operation quite efficient. Also, the 32K 
memory board is static, resulting in a reliable memory. 
The Tarbell System with all three cards can be 
expanded for more memory and thus provides the 
ultimate in flexiblity. 

Now Tarbell has it all. 




rSl&mf The ° neStop Sboppinq 



950 Dovlen Place, Suite B 
Carson, CA 90746 
(213) 538-4251 

MP/M is a trademark of Digital Research. 



Circle 123 on inquiry card. 



BYTE February 1981 189 



Technical Forum — ^— ^— ^_^^_ 

and is valid for most incandescent lamps. The most linear 
part of the curve is above the 60% illumination point. 
The nonlinearity is even more apparent in figure 2, which 
shows a standard calibration curve for theatrical SCR 
(silicon-controlled rectifier) dimmers controlling 120 V 
lamps from a 120 V RMS (root mean square) supply. The 
percentage of light output is also shown on the voltage 
axis. Note that 70 V RMS must be applied before the 
brightness reaches 10 % , and that raising the voltage from 
80 V to 109 V increases the brightness from 25 % to 75 % . 
Figure 3 shows the predicted RMS voltage applied to 
the load for trigger-delay angles from 0° to 179°, and also 
the percentage of light output corresponding to the ap- 
plied voltage. The angle versus volts curve was derived 
from the formula given in the SCR Handbook for triacs 
and back-to-back SCRs. The formula is: 



V 



LOAD(RMS) 



/27T 



(V-fl + 0.5(sin 2a)) 05 



constant illumination at 20% of the maximum brightness 
of the controlled lamp, the apparent brightness of the 
controlled lamp follows a Munsell curve somewhat 
similar to the Munsell curve relating the apparent 
loudness of a sound to its frequency and power. 

Because of these effects, theatrical dimmers, which 
receive a linear control voltage from the slide poten- 
tiometer, contain internal curve-generating circuits that 
cause the dimmer output to follow either the linear light 
curve of figure 2, or more usually the square law curve. 
The manner in which these curves relate linear dimmer 
motion to apparent light output is shown in figure 4 — it is 
evident that the square law curve provides the most 
linear relationship, at least for the theatrical stage. 

The eye is most sensitive in the region from 25% to 
85% of maximum light output. In this range, a sudden 
jump of 1 V produced by a delay count change is percep- 
tible, and jumps of 1.5 V to 2 V are quite obnoxious dur- 



where a (the firing angle) is in radians (not degrees), and 
E p is the peak value of the supply. 

Evaluating this equation with a BASIC program gave 
excellent experimental results. Using a 46 /is clock to 
drive the counter, computed values agree quite closely 
with this curve. (The true time for 1° per pulse is 
8333/180 = 46.294 /is, but the 46 /is clock is easily derived 
from a 1 MHz system clock and is only 1° off at 160° .) 

The human eye's response, too, is very nonlinear. 
When the area lit by a controlled lamp is surrounded by 




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2421 South Birch Street, Santa Ana, CA 92707 [71 4) 549-0623 
190 February 3983 © BYTE Publications Inc Circle 124 Ofl inquiry Card. 



i 

120 



-V RMS APPLIED TO LAMP 
I PERCENT LIGHT OUTPUT 



90 



60- 



50 



30- 




BLACKOUT 



2 3 4 5 6 7 8 

CONTROL VOLTS (E:) OR DIMMER SETTING 



10 
MAX 



Figure 2: Calibration curve for theatrical lamp dimmers. The 
control voltage is interpreted by the dimmer to produce a linear- 
seeming response. Note that the voltage actually applied to the 
lamp is not linear, but is related to the response of the lamp to 
voltage and the response of the human eye to light. 



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SSS FORTRAN & RATFOR are the critic's choice! 

The SSS FORTRAN compiler is fast, efficient, and complete (full 1966 ANSI 
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variables are supported. ROMable ".COM" files may be generated. 



FEATURES 

Code generation: ROMable ".COM" files or intermediate code files (saves disk 
space). External routines may be called. 

Data types: Byte, integer, real, double precision, complex, logical, charac- 

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Operations: All standard operations plus string comparisons, assignments, 

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Constants: Hexadecimal, decimal, and character literals with features to 

imbed control characters. 

Statements: ANSI 1 966 standard with multiple statement lines, state- 

ments may end with a ' ;'. 

Controls: Map, List, and Symbol table output options. 

I/O: Read, Write, Append, Rewind, Close, Delete, Rename, Search, 

sequencial and Random I/O on disk files. Supports all CP/M 
devices. The User can add device handlers to use custom I/O 
devices. 

Errors: Over 200 distinct compiler error messages, precision and 

illegal instruction warnings during execution. 

Interrupts: FORTRAN programs may be interrupted at any time: the stack 

pointer is always preserved. 



• • DC ATLEING • • 



SSS RATFOR 

RATFOR is a preprocessor that compiles to SSS FORTRAN. SSS 
RATFOR allows the use of contemporary loop control and struc- 
tured programing techinques. SSS RATFOR is similar to FORTRAN 
77 in that it supports such things as: 
REPEAT... UNTIL WHILE IF ... THEN ... ELSE 

Begin End Brackets Macro Defines 

SSS RATFOR is supplied with source code. The source code 
is distributed in both RATFOR and SSS FORTRAN. Not only does 
this prevent obsolescence, but allows the user to add enhance- 
ments as desired. 



iTTTTTTTTTTl 

System Requirements & Prices 

SSS FORTRAN requires a 32k CP/M system. Z80 only. 
SSS FORTRAN with RATFOR: $325.00 
SSS FORTRAN alone: $250.00 

RATFOR alone: $100.00 

(Sold only with valid SSS FORTRAN license) 

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SSS FORTRAN is the copyright of 
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SuperScft 

First in Software Technology 



BYTE February 1981 



191 



Technical Forum 



' RMS 



(LOAD) i % LIGHT 



120 




40 60 80 100 120 140 

TRIGGER DELAY ANGLE (DEGREES) 



Figure 3: Effect of trigger-delay angle on the RMS voltage ap- 
plied to the load of a thyristor-type dimmer. Plotted along with 
the percent of light output expected from an incandescent lamp, 
this curve is valuable for computer-controlled dimmer applica- 
tions. This curve is based on calculations made with a 46 us 
clock, which may be developed from a 1 MHz system clock. 



ing a long fade (eg: 20 seconds or more). To obtain a 
smooth fade, it is necessary that the linear timing pulses 
are translated to delay counts that will generate the 
square law curve. Also, since sudden changes are in- 
evitable with a digital dimmer, it is desirable that the 
magnitude of each incremental change is small, especially 
during a long fade. This implies increasing the number of 
steps so that smaller, more frequent voltage jumps wi)\ 
better approach the continuous change of an analog dim- 
mer. So far, I have obtained the best results by using an 
8-bit delay counter, which is not started until after a 
delay of 20° (920 fis); the range from 20° to 160° is then 
divided into 256 steps. The actual value loaded into the 
counter is obtained from a software table that converts 
linear increments to values that follow the square law. 

I have some cautionary notes to add, based on my own 
experiments. Triacs are much more persnickety and dif- 
ficult to control than a pair of back-to-back SCRs with a 
bridge to steer the trigger pulse. Unless great care is taken 
in the design of the dv/dt and di/dt damping networks, 
triacs generate a much larger amount of RFI (radio fre- 
quency interference), are more subject to "pulling," are li- 
able to be unpredictable and have infuriating interaction 
between channels on the same AC power phase. I have 
some doubt as to whether the simple RC (resistor/capaci- 
tor) damping networks shown by John Gibson in his fig- 
ure 9 will support multiple channels, all changing at dif- 
ferent rates in different directions, without interaction. A 
damped inductive filter is recommended by General Elec- 



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192 February 1981 © BYTE Publications Inc 



Circle 126 on inquiry card. 



How to develop 
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0-N703-0 Byte 



Circle 127 on inquiry card. 



BYTE February 1981 193 



Technical Forum, 



100 




LINEAR 
VOLTAGE 



4 5 6 

DIMMER SETTING 



Figure 4: Theatrical dimmer setting versus apparent light out- 
put. Internal curve-generating circuitry of most theatrical dim- 
mers follows either the linear light curve or the square law 
curve, as shown. 



trie, and I have found this type more effective in reducing 
RFI and interaction between channels. (See figure 5.) 

Also, triacs seem to be more vulnerable to spike 
overloads than SCRs. This becomes important when you 
realize that applying full voltage to a cold lamp filament, 
which has a very low resistance, causes an inrush current 



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Figure 5: A damped inductive filter for triac dimmers. By 
removing RFI with an effective filter arrangement, interaction 
between dimmers can be reduced. This is especially important 
when multiple channels are used to control lamps at differing 
rates and in different directions. 

spike that may peak at three to six times the normal full- 
brightness operating current of the lamp. While low- 
wattage lamps warm quickly, the thermal inertia of 
lamps rated at 200 W or more may allow the spike to be 
several milliseconds in duration and cause damage to the 
triac. Triacs are particularly vulnerable to such spikes, 
and I make it a rule never to load a triac to more than half 
its rated maximum current in applications where full 
voltage could be applied to a cold filament. 

Theatrical dimmers reduce inrush problems by keeping 
filaments warm with a blackout voltage of 12.5 V RMS. 
You may find that this results in a perceptible filament 
glow. If you reduce the blackout voltage to 6 V, you will 
kill the glow while still keeping the filaments warm 
enough to avoid inrush problems. 

Finally, I suggest that readers interested in precise light 
level control and color mixing should consult the follow- 
ing books: 

• The SCR Manual, 4th Edition. General Electric Co, 
1967 or later. This is the basic bible on proportional con- 
trol and SCR/Triac circuit design. 

• Sylvania GTE Lighting Handbook. Sylvania Co, any 
recent edition. This is a handy reference book on in- 
candescent lamps, fixtures, and space lighting principles. 

• CORTL1 (Computer Output of Real Time Lighting In- 
formation), The Mimi Garrard Dance Company, Soho 
Loft Theatre, 155 Wooster St, New York NY 10012, 
1978. (The cost is $10.) This describes a complete lighting 
system using digital dimmers under the control of an 
8080-based microcomputer: about fifty pages on how it 
came to be, over one hundred pages of detailed technical 
information, including detailed schematics and software 
listings in 8080 assembly language, and some operating 
information. It's very readable, and you get a tremen- 
dous amount of both solid information and speculation 
about future possibilities; likewise, it's an excellent source 
book for the money. The system works really well, too! I 
have seen it in action a number of times. ■ 



Technical Forum is a feature intended as an interactive 
dialog on the technology of personal computing. The subject 
matter is open-ended, and the intent is to foster discussion and 
communication among readers of BYTE. We ask that all cor- 
respondents supply their full names and addresses to be printed 
with their commentaries. We also ask that correspondents supply 
their telephone numbers, which will not be printed. 



194 Febiuary 1981 © BYTE Publications Inc 



Circle 128 on inquiry card. 



♦« 



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BYTE Febmary 1981 195 



Kmim)p> 



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Technical Forum 



Build a Null Modem 



Robert Haar, 1675 Thetford Rd, Towson MD 21204 



When connecting computers, terminals, and com- 
munication equipment, it is sometimes useful to have a 
device called a null modem. To understand what a null 
modem is and why you might need one, it is first 
necessary to know what a modem does and what is 
meant by the term RS-232C serial interface. 

Modems 

You probably have some idea of what a modem does. 
It allows computers and terminals to communicate over 
phone lines. This is done by converting serial binary data 
(individual bits transmitted one bit at a time) into audible 
tones that can be sent over normal telephone lines. 
Another modem at the opposite end translates these tones 
back into a stream of bits, which is then regrouped into 
8-bit bytes. Figure 1 is a diagram of this setup. The most 
common type of modem is called Bell 103 A compatible. 

RS-232C Serial Interface 

The term RS-232C refers to a standard that specifies 
the connection between a modem and either a computer 
or a terminal, covering the physical, electrical, and func- 
tional aspects of that interface. We are most familiar with 
the physical side of this standard since it describes the 
ubiquitous 25-pin D-shaped connector (the DB-25) that is 
used on most terminals and computer serial I/O (in- 
put/output) ports. The electrical aspects of the standard 
specify what kind of electrical signals can be applied to 
the pins of such a connection. The functional part says 
what the signals on each pin are supposed to mean. 

The modems shown in figure 1 are called DCE (data- 
communication equipment), while both the terminal and 
the computer are called DTE (data-terminal equipment). 
It makes no difference whether a unit is a terminal, a 
computer, or anything else — if it connects to a modem, it 
is DTE. One pin in the RS-232C connector is designated 
as a transmit-data line. This pin carries serial data from 
the DTE to the modem (DCE). Another pin is called re- 
ceive-data, and its data goes in the other direction. It is 
important to note that the transmit/receive designation is 
always defined in reference to the DTE-to-DCE connec- 
tion. 



Technical Forum is a feature intended as an interactive 
dialog on the technology of personal computing. The subject 
matter is open-ended, and the intent is to foster discussion and 
communication among readers of BYTE. We ask that all cor- 
respondents supply their full names and addresses to be printed 
with their commentaries. We also ask that correspondents supply 
their telephone numbers, which will not be printed. 



Null Modems 

The name "null modem" suggests a black box that 
looks like a modem but doesn't do anything. To see why 
you would need an "empty" modem, suppose that the 
terminal and the computer shown in figure 1 are in the 
same room and you wish to connect them together. You 
might be able to physically connect them if you have a 
cable with a DB-25P plug (male connector) on the end 
and the other has a corresponding socket, the DB-25S. 
But if both of them have been wired to connect to 
modems, you have a problem. Both will be sending infor- 
mation on the same transmit-data pin and both will be 
expecting to receive data from the other on the same 
receive-data pin. This would be equivalent to the effect of 
talking to someone on the telephone while the telephone 
handset is upside down. It just won't work. 

The simplest variety of null modem cross-connects the 
transmit- and receive-data lines as well as connecting the 
ground pins, which are required to establish a voltage 
reference for the other signals. In many instances, this is 
all you will need to allow the terminal and computer to 
talk to each other. In some cases, either the terminal or 
the computer requires other signals in addition to the 
data and ground lines. Table 1 lists the most commonly 
used pins in the RS-232C interface, along with their usual 
abbreviations and meanings. 



Pin Number and 




Name 


Function 


1 (AA) 


FG (frame ground), protective ground 




connection. 


2 (BA) 


TD (transmit data), from DTE to DCE. 


3 (BB) 


RD (receive data), DCE to DTE. 


4 (CA) 


RTS (request to send), the DTE asking 




permission to send to the DCE. 


5 (CB) 


CTS (clear to send), the DCE granting 




transmit permission. 


6 (CC) 


DSR (data set ready), indicates that the 




DCE is powered up. 


7 (AB) 


SG (signal ground), ground reference for 




the TD and RD signals. 


15 (DB) 


TC (transmit clock), clock used to 




generate the serial transmitted data 




(DCE to DTE). 


17 (DD) 


RC (receive clock), clock for received 




data (DCE to DTE). 


20 (CD) 


DTR (data terminal ready), indicates that 




the DTE is powered up. 


22 (CE) 


Rl (ring indicator), says that the incom- 




ing phone line is ringing; used with 




modems with answer capability. 


24 (DA) 


XTC (external transmit clock), like TC but 




from the DTE to the DCE. 


Table 1: Summary 


of RS-232C serial interface connections 


and their function. 





198 February 1981 © BYTE Publications Inc 



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Technical Forum, 



TERMINAL 



MODEM 



PHONE 
"LINE 



MODEM 



COMPUTER 



Figure 1: Diagram of a typical setup that allows a terminal to 
communicate with a computer over standard telephone lines. 
The modems shown are called DCE, or data-communication 
equipment, while both the terminal and the computer are called 
DTE, or data-terminal equipment. When referring to the RS- 
232C serial interface, the transmit/receive designation is always 
defined in terms of a DTE-to-DCE connection. 

Many terminals and computer serial I/O circuits 
generate the request-to-send and data-terminal-ready 
signals and expect to receive the corresponding signals 
clear-to-send and data-set-ready back from the modem. 
If these are not turned on, the DTE will not allow itself to 
transmit or receive data. If you plug together two pieces 
of equipment, both of which are configured as DTE, their 
data-terminal-ready and request-to-send signals will be 
connected together, and neither will know how to get the 
required data-set-ready or clear-to-send acknowledg- 
ments. Again, the solution is to cross-connect the cor- 
responding signals so that the DTR signal output of one 
device goes to the ready DSR input of the other and each 
unit's RTS signal goes to its own CTS input. 

The clock signals listed in table 1 are rarely used. If you 
need them, cross-connect them. Sometimes a device will 
need the ring indicator from a modem before it will start 
accepting incoming data. This can be obtained by con- 
necting this pin to the DTR pin of the other device. 




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CONNECTOR A 
PIN NUMBER 


1 


IFG) 


2 


(TD) 


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5 


(CTS) 


8 


(CD) 


7 


(SG) 


22 


(Rl) 


6 


(DSR) 


20 


(DTR) 



CONNECTOR B 
PIN NUMBER 



X 



n 



1 (FG) 

2 (TD) 

3 (RD) 

4 (RTS) 

5 (CTS) 
8 (CD) 
7 (SG) 
22 (Rl) 

6 (DSR) 

20 ( DTR ) 



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Figure 2: The interconnection scheme for a null modem. A null 
modem is a "black box" that allows two pieces of data-terminal 
equipment to communicate with each other when a phone line is 
not required (such as when they are in the same room). If the 
two pieces of equipment were connected without the use of a 
null modem, both would be sending information on the same 
RS-232C connector pin and also would expect to receive data on 
the same pin. 



Construction 

Figure 2 is a diagram of an interconnection scheme that 
works in most cases. If you need a different set of signals, 
it may be modified; table 1 provides the necessary infor- 
mation. In some cases you will need to connect a device 
that requires the DSR control signal to another that 
doesn't generate the corresponding DTR signal. In this 
event, connect the DSR pin of the first device to its own 
DTR pin. 

If you buy one of the commercially produced null 
modems, you will probably get a box about the size of a 
large paperback book, with two female connectors 
(DB-25S sockets). I found it more convenient to use one 
male and one female connector, because their pin 
numbers are mirror images of each other. Placing them 
back-to-back lines up all the pins with the same number. I 
bolted one-inch separators between the screw holes of the 
two connectors to hold them in place and then wired the 
connections as shown in figure 2. I wrapped the whole 
thing in electrical tape to seal it. The result is a much 
smaller package than the commercial product. It can easi- 
ly be attached to the end of the RS-232C cable and left 
there. 

Keeping to my practice of documenting whatever I 
produce, I drew a diagram like figure 2 on adhesive label 
material and placed it on the null modem's cover. If in the 
future I need to know which pins are connected, I won't 
have to remove the covering or hunt through my files for 
the circuit description. It is always right there. 

For Further Research 

If you would like more comprehensive information on 
this subject, consult chapter 26 of the book Technical 
Aspects of Data Communication by John McNamara, 
published by Digital Press. ■ 



200 February 1981 © BYTE Publications Inc 



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BYTE February 1981 



201 



Software Review 



IRV, a TRS-80 Utility Program 



Teri Li, POB 481, Peterborough NH 03458 



IRV is a new machine-language utility program for the 
BASIC programmer. It supplies features that all pro- 
grammers will appreciate, and it uses less than 1 K bytes 
of programmable memory (unless you add to its defini- 
tions). 

IRV gives you a flashing cursor, auto repeat on any 
key held down for more than one second, and keyboard 
control of the cassette remote plug (you can turn the 
cassette motor on and off simply by hitting shift-clear). 
[In this review, words in italics refer to keys of the same 
name as those on the TRS-80 keyboard.... GW] This is 
followed by the ability to define any key to your chosen 
definition. As sold by The Programmer's Guild, all of the 
shifted alphabetic keys are defined as BASIC keyword 
commands (see table 1); this duplicates features of the 
utility program called T-Short. 

However, if you don't like any of the provided defini- 
tions, you can easily change them by pressing the shift 



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and down-arrow keys, followed by the shift (alpha) key 
you want to redefine. When you have finished defining, 
press the shift-down-arrow combination once more. (Hit- 
ting enter merely inserts a carriage return into the defini- 
tion.) This ability to redefine is not restricted to alpha 
keys: it extends to all of the keys on the keyboard, except 
for the shift keys and the shift-down-arrow key combina- 
tion. This means that you can redefine both the break 
and enter keys! 

How is this possible? Simple: IRV pokes new addresses 
into the keyboard Device Control Blocks used by the 
TRS-80. The new addresses point to IRV, which is in high 
memory. IRV processes each input keystroke before call- 
ing routines in read-only memory. This gives IRV its 
great power and versatility. 

If you decide that you don't want the programmed- 
keys mode in operation, you can turn this feature off by 
hitting shift-down-arrow twice. To turn it back on, hit 
the shift-down-arrow twice again. 

The usefulness of these definable keys is not restricted 
to single BASIC commands; you can actually define a 
key as any message, command, or series of commands up 
to a maximum length of 255 characters. This is true for all 
of the keys. If you were to exercise this option to its 
fullest, you would fill almost 25 K bytes of program- 
mable memory (100 keys, uppercase and lowercase, 
times 255 characters per key). 

Yes, one keystroke can represent a series of commands. 
Hitting enter inserts a carriage return but does not end the 





Name: 
IRV 


Language: 

Z80 machine language 


Type: 

BASIC utility 

Manufacturer: 

The Programmer's Guild 

POB 66 

Peterborough NH 03458 


Computer: 

Radio Shack TRS-80, 
Model I with Level II 
BASIC and 16 K bytes or 
more of memory (disk 
drive optional for cassette 
version only) 


Price: 

Cassette $24.95 
Disk $29.95 


Documentation: 

5-page booklet, 14 by 22 
cm (5Vi by 8Yi in) 


Format: 

Cassette or 5-inch 
floppy disk 


Audience: 

BASIC programmers 



202 February 1981 © BYTE Publications Inc 



Circle 135 on Inquiry card. 



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BYTE February 1981 203 



Circle 137 on Inquiry card. 



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O 



Keystroke 


Result 


Keystroke 


Result 


shift-Q 


SYSTEM (enter) 


shift-Q 


GOTO 


shift-W 


RND( 


shift-H 


RIGHT$( 


shift-E 


ELSE 


shift-J 


INKEYS 


shitt-R 


RETURN (enter) 


shift-K 


CSAVE" 


shift-T 


THEN 


shift-L 


CLOAD 


shift-Y 


LEN( 


shift-Z 


EDIT 


shift-U 


USING 


shift-X 


STR$( 


shift-l 


INPUT 


shift-C 


CHR$( 


shift-0 


ASC( 


shift-V 


VAL( 


shift-P 


LPRINT 


shift-B 


INT( 


shift-A 


STRING$( 


shift-N 


NEXT 


shift-S 


GOSUB 


shift-M 


MID$( 


shift-D 


DATA 


shift-® 


CONT (enter) 


shift-F 


LEFT$( 


shift-right-arrow 


TAB( 


Table 1: One-keystroke strings supplied with IRV. When 


IRV is loa 


ded into the TRS-80, any of the 


single shifted 


keystrokes 


shown here will cause its associated string to be 


"typed" on 


the video display. 


(The word "enter" means that 


the last character typed is the 


same as pressing 


the enter key, 


thus causing the line to be executed.) These 


equivalencies 


may be < 


•.hanged or deleted by using the character- 


redefinitior 


mode. 







definition, so you can actually define one key to execute 
an entire series of commands when pressed. It will do this 
while executing either a machine-language or a BASIC 
program. For example, the back-up routine in TRSDOS 
(call BACKUP, answer all the questions: date, password, 
drives used, etc) can be abbreviated to a one-keystroke 
command. This is convenient, especially if you are 
duplicating several disks. 

One interesting advantage to IRV is that you can define 
the unshifted as well as the shifted keys. I used this 
feature to set up my keyboard to simulate the experimen- 
tal Dvorak typewriter layout. [The Dvorak system is a 
typewriter with a keyboard layout that increases speed 

and accuracy during touch-typing GW] Other 

possibilities could include rearranging the keys to accom- 
modate foreign languages that use the standard Roman 
alphabet, but use letters in frequencies different from 
English. 

At this point, IRV is far superior to T-Short and other 
keystroke shorthand routines. But IRV does not stop 
here: it has even more capabilities. 

IRV gives you on-screen BASIC line editing similar to 
the on-screen line-editing features of the Commodore 
PET. To use this feature, first list your program on the 
video, then hit the shift-break key combination. The 
blinking rate of the cursor will change slightly. Now you 
can use the four arrow keys to move the cursor anywhere 
you like on the video screen. Full-screen wraparound is 
supported: if the cursor leaves the screen from the bot- 
tom, it will appear at the top of the screen in the same col- 
umn; leaving the screen to the right will put the cursor on 
the left of the same line. 

Once you have put the cursor on the line in which you 
are interested, you may type anything you want over the 
line. If there are too many characters on the line, hitting 
the clear key will delete 1 character. If you need more 
room, each time you press the break key one space will 
be added, over which you may type. Holding down 
either key for more than one second causes each key to 
repeat its function as long as the key is depressed. 



204 February 1981 © BYTE Publications Inc 



Circle 138 on inquiry card. 



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BYTE February 1981 205 



Circle 140 on inquiry card. 



IEEE-488 To TRS-80* INTERFACE 



■ I SCIMIFIC UfiHEKIIC IAHWKS1ES I 




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(a) 



FIRST, WRITE A SHORT BASIC 
PROGRAM TO PUT THIS GRAPHICS 
FIGURE ON SCREEN 




(b) 



100 MAN $(1) = " 
105 MAN $(2) = " 




j j 



j j 



Figure 1: Use of IRV to directly create graphics in BASIC pro- 
grams. First write a short BASIC program that creates the shape 
you want to use. Running this program displays the shape on 
the video screen, as shown in figure la. Then use the line-editing 
feature of IRV to create BASIC statements (either PRINT or 
string-storage statements) that capture the shape, one text line at 
a time. In figure lb, the shape is stored in two entries of the 
string array MANS. Later, these graphic characters can be 
printed out in the same program using PRINT statements. 



If you are adding spaces to a line, you will notice that 
repeated addition of characters does not move the 
rightmost character down to the next line on the video 
display — instead, it causes the character to disappear 
from the screen. Likewise, if you have removed all the 
characters to the right of the cursor, the first character on 
the next line does not move up. The reason is that IRV 
looks only at the line on which the cursor is set. 

When the line is set to your liking, hit enter. This 
transfers the changes you have made in that line to the 
program. If you list the line, you will be able to see that 
the changes have been made. Should you discover that a 
line is misplaced, you can use this line-editing feature to 
type a new number over the old line number. When you 
hit enter, the new line will be inserted into its proper 
place in your program, and the old line will still be in its 
place. This feature is handy for moving lines around in 
your programs. 

The best advantage of the line-editing feature in IRV is 
that it may be invoked while in the TRS-80 edit mode. 
For example, it can be used to string several BASIC 
statements into one long multiple-statement line. Edit the 
line as you would normally, but when you are ready to 
insert, hit shift-break. Now position the cursor over the 
line that you wish to insert in the line being edited. Use 
the clear key to remove the line number (you don't want 
to insert a line number), then hit enter. List the edited line 
and you will see that both lines have merged: the second 
line is positioned where you entered the insert mode. 
Other uses include converting IF... THEN statements to 
IF... THEN... ELSE statements, or vice versa. 

Still another use for the IRV line editor is to put 
graphics characters directly into PRINT statements. First, 
use a short graphics routine to draw your figure on the 
video display. When you've finished with the drawing, 
enter the IRV line-editing mode. Type a line number 



206 Febiuary 1981 © BYTE Publications Inc Circle 141 On Inquiry Card. 



ITEM NO. 
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14-16 EXTRACTOR 

24-40 CMOS SAFE EXTRACTOR 



OK MACHINE & TOOL CORPORATION 

3455 CONNER ST., BRONX, N.Y. 10475 U.S. A. 

PHONE 12121 991-6600 TELEX NO 125091 



RINTED IN U.S.A. 



PATENT PENDING 




INS-1416 


14-16 PIN DIP IC INSERTER 


$ 3.49 


MOS-1416 


14-16 PIN MOS CMOS SAFE INSERTER 


$ 7.95 


MOS-2428 


24-28 PIN MOS CMOS SAFE INSERTER 


$ 7.95 


MOS-40 


36-40 PIN MOS CMOS SAFE INSERTER 


$ 7.95 


EX-1 


14-16 PIN EXTRACTOR TOOL 


$ 1.49 


EX-2 


24-40 PIN CMOS SAFE EXTRACTOR TOOL 


$ 7.95 


WK-7 


COMPLETE IC INSERTER/ EXTRACTOR KIT 


$29.95 



MINIMUM BILLING J25.00. ADD SHIPPING CHARGE $2.00. NEW VORK RESIDENTS ADD APPLICABLE TAX. 



OK MACHINE & TOOL CORPORATION 3455 CONNER ST., BRONX, N.Y. 10475 (212) 994-6600/TELEX 125091 



Circle 142 on inquiry card. 



BYTE February 1981 207 



Circle 143 on Inquiry card. 




Model EP-2A-88 

EPROM Programmer 




Fast as Jackrabbits . . . Well, almost! 

In Australia, two rabbits can reproduce over 13 million offspring in 
3 years ... at 105 seconds for 2706's. the EP-2A-88 can reproduce 
1,892,160 EPROMS in 3 yeai-s. Single push button control, the 
EP-2A-88 checks if EPROMS are erased, programs and verifies. 
It also checks for defective EPROMS. 

Two basic models are available, The EP-2A-88-1 will accept Copy 
(CM) modules for the 2758, and 2716 EPROMS. The EP-2A-88-2 
will accept copy modules for the 2716, 2732 and TMS 2532 
EPROMS. Power requirements are 115 VAC 50/60 Hertz at 15 
watts. 

Pari No. Description Price 

EP2A88 1 EPROM Programmer $490.00 

EP 2A 88 2 EPROM Programmer 490.00 

CM-50 Copy Module for 2716. TMS 2516 EPROMS 25.00 

CM 70 Copy Module lor 2758 EPROMS 25 00 

CM 20 Copy Module lor 2732 EPROMS 25 00 

CM 40 Copy Module lor TMS 2532 EPROMS 25.00 

Non Standard Voltage Option (220 v. 240 v. KXlu] 15 00 

Optimal Technology, Inc. 

Blue Wood 127, Earlysville, Virginia 22936 
Phone (804) 973-5482 



directly onto the screen, then the word PRINT, and put 
quotes in front and at the end of the graphics characters. 
When you hit enter, that line will be entered into BASIC 
as a new line. When you list the line, you will see the 
graphics characters printed as BASIC keywords, but 
when you execute the line, the graphics figure will be 
drawn on the screen. You can also set the drawings equal 
to strings (see figure 1). 

Implementation Details 

IRV can be purchased in 5-inch floppy disk or cassette 
form. The cassette version has instructions for saving the 
file to disk; disk-based users may want to do this, even 
though the program takes exactly 17 seconds to load 
from cassette. Different versions of IRV are loaded (from 
either cassette or disk) depending on whether your 
TRS-80 has 16 K, 32 K, or 48 K bytes of memory. All 
three programs are contained on either the disk or 
cassette versions of IRV. You must also answer the 
MEMORY SIZE? prompt when entering BASIC in order 
to allow sufficient space for the storage of IRV and its key 
redefinitions. This is simple to do and is explained in the 
IRV booklet supplied with the software. 

IRV is available from several software suppliers, in- 
cluding The Programmer's Guild (POB 66, Peterborough 
NH 03458), The Software Exchange (6 South St, Milford 
NH 03055), and Scott Adams' Adventure International 
(POB 3435, Longwood FL 32750). IRV is sold with 
predefined keys (see table 1) and will operate in both 
Level II and disk BASIC. It is compatible with TRSDOS, 
NEWDOS, and OS-80. For those of you with new- 
version Level II ROMs (or read-only memories, which 
power up with the abbreviated message R/S L II BASIC 
instead of spelling out all the words), there is also a ver- 
sion of IRV that will operate on your keyboards: just 
specify that you have the new Level II ROMs. 

Conclusions 

• IRV is a versatile piece of utility software for the 
TRS-80 Model I BASIC programmer. It allows you to 
redefine any keystroke as any character or series of 
characters, and to modify BASIC programs by simply 
typing over a listing of the program. 

• IRV can be used to renumber BASIC lines or to merge 
several lines or parts of lines without having to retype the 
lines involved. This is a valuable aid when modifying an 
existing program. 

• IRV can be used to turn the cassette motor on and off 
without repeatedly plugging and unplugging the remote 
motor-control plug; this is a great help when trying to 
work with cassette tapes. 

• IRV gives every key an auto-repeat facility. 

[Editor's note: IRV is one of the most exciting pieces of 
software I've seen in a long time, primarily because it 
allows you to devise uses for it that are not specifically 
planned by the software designers. For example, when 
editing a line of BASIC code, you can use a single key 
that is defined as ten copies of the string "S D" (each of 
which will search for a blank and delete it) to take all of 
the spaces out of a line: this speeds up the task at hand by 
eliminating dozens of keystrokes. Because of its open- 
ended design, IRV can be used in a variety of situations, 
and I feel that it is as important and innovative as the 
popular VisiCalc program. Philip Mork, the author of 
IRV, is to be commended for his fine work. . .GW]| 



208 February 1981 © BYTE Publications Inc 



Circle 144 on inquiry card. 



Now NRI takes you inside the 

new TRS-80 Model III microcomputer 

to train you at home as the 

new breed off computer specialist! 



NRI teams up with Radio Shack 

advanced technolo y to teach 

you how to use, program and 

service state-of-the-art 

microcomputers... 
It's no longer enough to be just a 
programmer or a technician. With micro- 
computers moving into the fabric of our 
lives (over 200,000 of the TRS-80™ 
alone have been sold) , interdisciplin- 
ary skills are demanded. And NRI 
can prepare you with the first 
course of its kind, covering the com- 
plete world of the microcomputer. 
Learn At Home 
in Your Spare Time 

With NRI training, the program- 
mer gains practical knowledge of hard- 
ware, enabling him to design simpler, 
more effective programs. And, with ad- 
vanced programming skills, the techni- 




T raining Includes new TRS-80 Model III micro- 
computer, solid state volt-obm meter, digital 
frequency counter, and the NRI Discovery Lab 
with hundreds of tests and experiments. 

(TRS-80 is a trademark of the Radio Shack division of landy Corp.) 




cian can test and debug systems quickly 
and easily. 

Only NRI gives you both kinds of 
training with the convenience of home 
study. No classroom pressures, no night 
school, no gasoline wasted. You learn at 
your convenience, at your own pace. Yet 
you're always backed by the NRI staff 
and your instructor, answering questions, 
giving you guidance, and available for 
special help if you need it. 

You Get Your Own Computer 
to Learn On and Keep 

NRI training is hands-on training, 
with practical experiments and demon- 
strations as the very foundation of your 
knowledge. You don't just program your 
computer, you introduce and correct 
faults. . .watch how circuits interact. . . 
interface with other systems . . . gain a 
real insight into its nature. 

You also build test instruments and 
the NRI Discovery Lab, performing over 
60 separate experiments in the process. 
You learn how your trouble-shooting tools 
work, and gain greater understanding of 



the information they give you. Both mi- 
crocomputer and equipment come as part 
of your training for you to use and keep. 
Send for Free Catalog. . . 
No Salesman Will Call 

Get all the details on this exciting 
course in NRI's free, 100-page catalog. It 
shows all equipment, lesson outlines, and 
facts on other electronics courses such as 
Complete Communications with CB, TV 
and Audio, Digital Electronics, and more. 
Send today, no salesman will ever bother 
you. Keep up with the latest technology 
as you learn on the latest model of the 
world's most popular computer. If card 
has been used, write to: 

NRI Schools 

McGraw-Hill Continuing 
Education Center 
■VSl'ii 3939 Wisconsin Avenue 
■ ■nil Washington, D.C. 20016. 




BYTE February 1981 



209 



Maximum 
Functions 

Minimum 
Space 

Maximum 
versatility 

Minimum 
Price: 

SYSTEM 
SUPPORT 1 



If you ever need to crunch numbers, time 
i ntervals or events, create sequenced 
programs, check for power interruption, 
shuttle information through an RS-232C serial 
port at up to 19,200 Baud, tell your computer to 
do somethingat 02:47:37 AM on March 24th of 
1982, employ 15 levels of interrupts, 
or need EPROM or battery-backup RAM to 
accomplish any of the above. . .and want to do 
all this while fully conforming to all IEEE 
696/ S-1 00 standards. . .System Support 1 is 
here. 

Call (415) 562-0636,9 AM to5PMPST,for 
the name of a CompuPro retailer nearyou. 



System Support 1 prices: $295 Unkit, S395 A/T , $495 qualified under 
the Certified System Component high-reliability program. Math 
processor and ROM/RAM optional at extra cost. Pricesshown do not 
include dealer installation and support services. 



CompuPro™ 

^OAkRnTOrPOR^A94614 



SQI 

4513231 
1789216 
024867 
579460 





battery backup 
for one socket 



ELECTRONICS 

210 BYTE February 1981 




Circle 145 on inquiry card. 



THE COMPUPRO SYSTEMS APPROACH: 

Unlike "all-in-one" computers, CompuPro's modular S-100 systems HTP* TT POW^fTR 

are amazingly flexible machines that are ideal for high level industrial 111U11 1 VTT J^JA, 

commercial, and scientific applications. Full conformance to all IEEE TJTi° W P¥TT?17rf~IT?lVf A ATI" 1 !? 

696/S-100 specifications ensures well integrated systems performance, XXXvfXX I MliMXF \JM\LVH\1 1 Vjt^ 

as well as freedom from obsolescence in the years to come. A rVTTk ITiriTT rrfTnATTniTnTTrr, 

All CompuPro products meet the most demanding mechanical AIMD Xllljjl rUlOU (tH PI IT 
and electrical standards, accept the highest possible clock speeds for 

maximum throughput and are backed with one of the best - if not the best - warranties in the business (1 year limited warranty on all products 
2 year limited warranty for boards qualified under the Certified System Component program) 

When you're looking for a computer, there are lots of choices. But when you need a precision machine that is built for the future as 
well as the present, the choice narrows down to the most experienced name in the S-100 business: CompuPro 




NEW! COMPUTER ENCLOSURE 2 

Introductory price: $795 

Specify rack mount or desk top version. 

We just made it easier for you to move up to an expandable 
S-100 system. . .COMPUTER ENCLOSURE 2 is ready to accept 
boards the minute it's unpacked. Heavy-duty, fused, constant 
voltage power supply provides +8 V at 25 Amps (I), + 16V at 3 
Amps, and -16V at 3 Amps; 20 slot shielded motherboard, with 
active termination, offers high speed performance. Other 
features include dual AC outlets on rear, heavy-duty line filter, 
circuit breaker, quiet ventilation fan, reset switch, and black 
anodized front panel (with textured vinyl painted cover for 
desktop version). Rack mount version includes slides for easy 
pull-out from rack frame. 

Also available: COMPUTER ENCLOSURE 1. Same as above, 
but less power supply and motherboard. $289 desktop, $329 
rack mount. 



LOWEST PRICE EVER ON 

16K DYNAMIC RAMS - 8/$37 

Just what you would expect from the memory leader: top 
quality, low power, high speed (200 ns) 16K dynamic RAMs, 
backed up with a 1 year limited warranty. Expand memory in 
TRS-80* -I and -II computers as well as machines made by 
Apple, Exidy, Heath H89, newer PETs, etc. Add $3 for two dip 
shunts plus TRS-80" conversion instructions. Limited quantity. 



S-100 HIGH PERFORMANCE 

MOTHERBOARDS 

Actively terminated and fully shielded, these advanced 
motherboards handle the coming generation of 5 to 10 MHz 
CPUs as well as present day 2 and 4 MHz systems. Mechanically 
compatible with most computer enclosures. Unkits have edge 
connectors and termination resistors pre-soldered in place for 
easy assembly. 

20 slot motherboard with edge connectors - Unkit $174, A/T $214 
12 slot motherboard with edge connectors - Unkit $129, A/T $169 
6 slot motherboard with edge connectors - Unkit $89, A/T $129 



SOFTWARE 

PASCAL/M* : $175 complete 

PASCAL - easy to learn, easy to apply - can give a 
microcomputer with CP/M 18 more power than many minis. We 
supply a totally standard Wirth PASCAL/M* 8" diskette and 
comprehensive manual. Specify Z-80* or 8080/8085 version. 

8088/8086 MONITOR-DEBUGGER: $35 

Supplied on single sided, single density, soft-sector 8" disc. 
CP/M* compatible. Great development tool; mnemonics used 
in debug conform as closely as possible to current CP/ M'" DDT 
mnemonics. 



HIGH SPEED S-100 CPU BOARDS 

8 BIT CPU Z 

Like many others, we claim full conformance to IEEE 
696/S-100 specifications; unlike many others, we'll send you 
the timing specs to prove it. CPU Z includes all standard Z-80A' 
features along with power on jump, on-board fully maskable 
interrupts for interrupt-driven systems, selectable automatic 
wait state insertion, provision for adding up to 8K of on-board 
EPROM, and 16/24 bit extended addressing. Works with 6 MHz 
CPUs; supplied with 4 MHz CPU. $225 Unkit, $295 A/T, $395 
CSC. 

16/8 BIT CPU 8085/88 

When we shipped the first CPU 8085/88 board back in June of 
1980, we created a bridge between the 8 bit world of the present 
and the 16 bit world of the future. By using an 8088 CPU (for 16 
bit power with a standard 8 bit bus) in conjunction with an 8 bit 
8085, CPU 8085/88 is downward compatible with 8080/8085 
software, upward compatible with 8086/88 software (as well as 
Intel's coming P-Series), designed for professional-level high 
speed applications, and capable of accessing 16 megabytes of 
memory. . .while conforming fully to all IEEE 696/S-100 
standards (timing specs available on request). 

Looking for a powerful 8 bit CPU board? Looking for a 
powerful 16 bit CPU board? Then look at CPU 8085/88, the best 
of both worlds. 

Prices: $295 Unkit, $425 A/T (both operate at 5 MHz); $525 
CSC (with 5 MHz 80B5, 6 MHz 8088). Owner's manual available 
separately for $5. 

8 BIT CPU 8085 

This is a single 8 bit processor version of the above board, 
and may be easily upgraded to full 16 bit operation at a later 
date. $235 Unkit, $325 A/T, $425 CSC. 




MPX 1: THE ANSWER TO COST-EFFECTIVE 

MULTI-PROCESSING 

MPX 1, a powerful front end processor/system multiplexer, 
unloads the host CPU to handle heavy 8 or 16 bit 
multi-user/multi-task traffic. This results in greatly increased 
throughput and speed of operation. MPX includes an on-board 5 
MHz 8085 microprocessor, 2K of ROM, 4K or RAM, interrupt 
controller, and much more. Finally. . .multi-processing is an 
affordable reality. Call for pricing and delivery information. 



OTHER S-100 BUS PRODUCTS 

Active Terminator Board $34.50 Kit 

Memory Manager Board $59 Unkit, $85 A/T, $100 CSC 

Mullen Extender Board $59 Kit 

Mullen Relay/Opto-lsolator Control Board . $129 Kit, $179 A/T 

Spectrum color graphics board $299 Unkit, $399 A/T, $449 CSC 

2708 EPROM Board (2708s not included) $85 Unkit, $135 A/T, $195 CSC 

InterfaceM (dual RS-232 serial ports) $199 Unkit, $249 A/T, $324 CSC 

Interfacer 2 (3 parallel + 1 serial port) $199 Unkit, $249 A/T, $324 CSC 



S-100 MEMORIES FROM THE MEMORY LEADER 

CompuPro memories feature fully static design to eliminate dynamic timing 
problems, full conformance to all IEEE 696/S-100 specifications, high speed operation 
(4/5 MHz Unkit, 10 MHz A/T and CSC), low power consumption, extensive bypassing, 
and careful thermal design. 

Unkit 

8KRAM2A $159 

16K RAM 14 (extended addressing) $279 

16K RAM 20-16 (extended addressing and bank select) $319 

24K RAM 20-24 (extended addressing and bank select) $429 

32K RAM 20-32 (extended addressing and bank select) $559 

12BK RAM 21-128 (extended addressing) n/a 



A/T 


CSC 


$189 


$239 


$349 


$429 


$399 


$479 


$539 


$629 


$699 


$799 


n/a 


$2795 



Most CompuPro products are available in Unkit form, Assembled/Tested, or 
qualified under the high-reliability Certified System Component (CSC) program (200 
hour burn-in, extended 2 year warranty, more). Please note that unkits are not 
intended for novices, as de-bugging may be required due to problems such as IC 
inlant mortality. Factory service is available for Unkits at a flat service charge. 

TERMS: Prices shown do not Include daalBT Installation and support servlcas. Cal res add tai. 
Allow al least 5% shipping: excess refunded. Orders under SIS add S2 handling. VISAS and 
Mastercard orders (S25 ffttfi) call (415) 562.0636, 24 hrs. Please include street address (or UPS 
delivery. Prices are subject to change without notice. 

FREE CATALOG: Wanl more information? Then send lor our Iree catalog. For 
last 1st class delivery, add 41 cents in stamps; foreign orders add $2 (refundable with 
order). 

'LEGAL CORNER. ZSOAisa registered trademark of Zilog; TRS-80 is a trademark of the Tandy 
Corporation: PASCAL'M is a trademark of Sorcim: CP'M is a registered trademark of Digital 



COMPUPRO PRODUCTS ARE AVAILABLE 
AT FINER COMPUTER STORES WORLD-WIDE. . . 

CALL (415) 562-0636 FOR THE STORE NEAREST YOU. 

Circle 145 on inquiry card. 



CompuPro M 



(BP@®00iJ 

W^ ELECTRONICS ^ 



OAKLAND AiriHOHi, CA «46I4 



ELECTRONICS 
(415)562-0636 

BYTE February 1981 211 



BYTELINES 



News And Speculation About Personal Computing 



Conducted by Sol Libes 



U, 



'NIX Standard Called 
For: "/usr/group" is a newly 
formed group for users of 
UNIX and UNIX-like oper- 
ating systems. At a recent 
group meeting, a Western 
Electric representative 
disclosed that his company 
has granted approximately 
156 commercial licenses at 
about 244 commercial sites. 
Many present at the meeting 
complained about Western 
Electric's excessive charges 
for unsupported software. 
The company typically 
charges $12,000 for a single 
processor license and as 
much as $40,000 for users of 
the DEC [Digital Equipment 
Corporation) VAX machines. 

UNIX users, now faced 
with many different im- 
plementations of UNIX, are 
beginning to be concerned 
with standards. To help cope 
with the problem the group 
plans to issue a UNIX Users 
Cu/'de. 

Also at the meeting, 
Microsoft announced plans 
for implementations of its 
Xenix package on the Texas 
Instruments TI9900, IBM 
Series/1, and Point 4 Data 
Corporation systems. 

For more information 
write, /usr/group, POB 8570, 
Stanford CA 94305. 



u 



' CSD Pascal 4.0 To Be 
Released: A new version of 
UCSD Pascal will soon be 
released by Softech Micro- 
Systems. The good news is 
that Pascal 4.0 will have 
many new features, such as 
multitasking and better 
screen handling. In other 
words, it will be more flexi- 
ble, do more jobs, and be 
generally more powerful. 

The bad news is that it will 
generate code that includes 
four new p-code instruc- 
tions. Hence, the Pascal 
MicroEngine, presently the 
fastest available Pascal 



system, will not be compati- 
ble with the new 4.0 version. 
Of course, WD (Western 
Digital) can recode the 
MicroEngine microcode 
ROMs (read-only memories) 
to include the new instruc- 
tions, but I don't know. Con- 
sidering that it took WD 
nearly a year to come out 
with the present ROM set, I 
do not foresee the possibility 
of MicroEngine Pascal 4.0 
for some time yet. 



Vo 



olce Entry System 
For The Apple: Scott In- 
struments, Denton, Texas, 
will introduce an Apple ver- 
sion of its voice entry 
system. To be called 
"Applevet," this system will 
be able to recognize as 
many as 680 words or ut- 
terances. An $895 price tag 
for the system will include a 
plug-in board, a noise-can- 
celing microphone, and de- 
monstration disk. 



Vo 



olce-Operated Tele- 
phone Dialer Tested: 

Bell Labs, Murray Hill, New 
Jersey, has disclosed that it 
is testing a telephone dialer 
that is voice operated. The 
caller can ask for a 4-digit 
telephone extension or a 
name in the directory of the 
system, and the system will 
then dial the number. The 
dialer has already demon- 
strated a high reliability. If in 
doubt as to what it is told, it 
asks the caller to repeat the 
entry. 

The system uses a high- 
speed array processor at- 
tached to a minicomputer to 
detect the presence of 
speech and identify voice 
features to be used by a 
word recognizer. The word 
recognizer compares the 
features of the utterance to 
a subset of stored features 



and generates a word-candi- 
date list, which is ordered 
according to the probability 
of the word's occurrence. 
The system uses a feature 
template of the caller's 
voice, learned during a train- 
ing period, to recognize the 
caller's voice input and dial 
the number. The system re- 
cognizes only isolated word 
inputs, and the user must 
speak slowly and haltingly. 



w. 



here Are The 
64 K-BIt Memory ICs7 

At one time, memory size 
quadrupled every two years. 
But four years have now 
elapsed between the in- 
troduction of the 16 K-bit 
and the 64 K-bit memory 
ICs. Skyrocketing develop- 
ment costs and difficulties in 
working with such dense 
devices have caused most of 
the delay. It is likely that the 
next quadrupling will take 
even longer. 

Over two dozen suppliers 
are now delivering samples 
of 64 K-bit programmable 
memories to computer 
manufacturers; some of the 
samples are already in 
limited production. You can 
expect to see the first prod- 
ucts using 64 K-bit in- 
tegrated circuits in the third 
or fourth quarter of this 
year. However, do not look 
for their widespread use un- 
til sometime in late 1982 or 
1983, when prices should 
drop to under $10 each. 

American memory manu- 
facturers are extremely con- 
cerned about Japanese com- 
petition in this area, 
however. The first company 
to supply 64 K-bit circuits 
was Fujitsu Ltd, and eight 
other Japanese manufac- 
turers are jumping in too. 
Some manufacturers fear 
that the Japanese may snare 
60% to 70% of the 



64 K-bit memory market. If 
this occurs, the entire 
American computer industry 
may find itself in trouble. 



^mpple Stock Goes On 
Sale: Shares in Apple Com- 
puter Inc, one of the most 
eagerly awaited public stock 
offerings, went on sale early 
in December 1980. Apple of- 
fered 8% of the company's 
52.4 million shares (ie: 4.6 
million shares) at a price of 
$22 per share. 

Apple, incorporated in 
1977, reported profits of 
$11.7 million on sales of 
$117 million for the fiscal 
year ending September 26, 
1980. 1979's earnings were 
$5 million on $48 million 
sales, and, in 1978, sales 
were $7.8 million with pro- 
fits of $793,497. 

Steve Jobs, 25 years old, 
and Steve Wozniak, 30 years 
old, the creators of the 
Apple computer, each hold 
8.3 million shares. That 
means that they own well 
over $100 million worth of 
stock. A C Markkula, 32 
years old, who took Apple 
from a garage operation to 
its current enviable position, 
also holds 8.3 million shares. 
Venrock Associates, a ven- 
ture capital firm, holds 3.8 
million shares. Significant 
blocks are held by several 
other venture capital con- 
cerns. Xerox holds 80,000 
shares. 



ultatus Report On The 
IAPX-432: Late last spring, 
Intel announced its iPAX-432 
32-bit microprocessor with 
great fanfare. At that time, 
only very general specifica- 
tions were released and sub- 
sequently reported on in this 
column. (See "Intel Releases 
Data On 32-Bit Microproces- 



212 February 1981 © BYTE Publications Inc 






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Report Writer 

trademark Carolina Business Computers 

Selector IV trademark Micro-Ap Pearl trademark 

ot CPU Int'l Pascal/M, ACT & TRANS 86 trademarks Sorcim 

CBASIC2 trademark Compiler Systems Mogic Wand trademark Small 

Business Applications Textwriter, Datebook & Milestone trademarks Organic Software 

Ultrasort-ll & FABS trademarks Computer Control Systems Magic Menu trademark of Charles Merrirt 

Copywriter, Copyproof & Diction trademarks Systronlcs Microstat trademark Ecosoft S-Basic trademark Topaz Programming 

Spellguard trademark ISA CP/M_& MP/M trademarks Digital Research TRS-80 trademark Tandy Superbroin trademark Intertec Data 



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System's UCSD Pascal trademark of Regents of University of California WordStdr trademark Micro Pro Inn Spellbinder trademark Lexisoft 
For shipping add S5. In US; $10. outside US per package California residents add appropriate stale sales tax Terms: Prepaid check, 
M/C or VISA or In US COD (UPS) Dealer Inquiries Invited Prices quoted do not include dealer Installation & training Prices effective until April 1, 1981 



Circle 146 on Inquiry card. 



BYTE February 1981 



213 



BYTELINES 



sor," August 1980 BYTE, 
page 94.) During the fall, 
however, Intel made large- 
scale presentations to sev- 
eral major systems-level 
houses. Rumor has it that 
Intel will deliver a paper at 
the International Solid State 
Circuit Conference (ISSCC) 
this month, in which it will 
divulge full details on the ar- 
chitectural design of the 
iAPX-32. Intel should start 
delivering samples within 
another month or two. 

The iAPX-32 is a 3-chip set 
that uses more than 100,000 
transistors per IC (all 64-pin 
packages). The design of the 
instruction set is aimed at 
supporting high-level com- 
piled programs written in 
Pascal, Ada, and FORTRAN. 

Intel had also let it be 
known that it planned to 
supply microcoded firmware 
in the processor device that 
would directly execute the 
Ada high-level language. 
However, rumor currently 
has it that Intel is retreating 
from this concept. 



Status Report On 
1 6-Blt M Icrocomputers: 

The 16-bit scene matured 
during 1980. Intel sold about 
200,000 of its 8086 devices 
(at well over $100 apiece, 
Intel appears already to be 
profiting from this unit). By 
midyear, Zilog had managed 
to remove the bugs from the 
Z8000 and, by year's end, 
was in full production. 
Motorola must be given 
credit for designing the most 
powerful 16-bit microproces- 
sor (imagine having seven- 
teen 32-bit-wide registers 
and 23-bit addressing to 
reach 16 megabytes of 
memory directly). It must be 
considered a landmark 
achievement that Motorola 
was actually shipping 
limited production quan- 
tities of fully functional 
68000 devices by the end of 
1980 that met specifications. 
This is particularly im- 
pressive when you consider 
the number of elements in 
the device (about 70,000) 
and the large size of the 
silicon chip (246 by 280 
mils). 



In production now for two 
years, the 8086 is just begin- 
ning to develop a respec- 
table software base. For ex- 
ample, Digital Research is 
starting to supply an 8086 
version of CP/M. The soft- 
ware bases for the Z8000 
and 68000 are still extremely 
limited and are probably 
more than a year behind the 
8086 software base. 

National Semiconductor 
expects to start shipping 
samples of its new 16032 
16-bit chip set, which prom- 
ises features similar to the 
DEC (Digital Equipment Cor- 
poration) 32-bit VAX ma- 
chines. The silicon area on 
this device (250 by 300 mils) 
is even larger than 
Motorola's 68000. Industry 
observers concede that this 
set of devices is significantly 
more powerful than the 
68000, the Z8000, or the 
8086. However, many obser- 
vers doubt whether National 
will be able to compete with 
Intel, Zilog, and Motorola, 
because of its late start and 
the great expense of such a 
project. 



■Soviets Develop 

8080A-Llke Micropro- 
cessor: According to a 
technical report released by 
CDC (Control Data Corpora- 
tion), the Soviet Union is 
manufacturing a micropro- 
cessor that is very similar to 
Intel's 8080A design. Control 
Data obtained samples of 
the integrated circuit from 
the Hungarian government, 
and promptly dissected it. 
They discovered that the 
device, called the 
K80IK8077, uses the same 
circuit blocks as the 8080A, 
except that it is adapted for 
the NMOS (n-channel metal- 
oxide semiconductor) pro- 
cess. 

In the manufacturing pro- 
cess, Soviet technicians 
relaxed line widths and 
geometry separations and 
used a larger chip size (214 
by 192 mils, compared to 
193 by 171 mils for Intel, 
which Intel later reduced to 
165 by 161 mils). The Soviet 
design is thus more conser- 



vative and more expensive 
to produce. CDC identified 
several "workmanship 
flaws" in the devices (eg: 
questionable die attach- 
ments and scraping of bond 
wires). CDC felt that the 
Soviet technology was equal 
to American technology, 
vintage 1977. The device 
uses a 48-pin package with 
eight unused pins. 



H 



ome-Banklng/ 
Information System 
Inaugurated: Radio 
Shack, CompuServe, and 
United American Service 
Corporation have joined 
forces to inaugurate a na- 
tionwide home-banking and 
information system. (See 
"You Can Bank on It," 
January 1981 BYTE, page 
10.) Using the new TRS-80 
Color Computer, a television 
receiver, and a modem, a 
subscriber will be able to 
pay bills, obtain a bank 
statement, do bookkeeping, 
apply for a loan, send and 
receive electronic mail, and 
access the CompuServe data 
base. The service will cost 
between $15 and $25 a 
month. United American ex- 
pects to have forty banks 
and 20,000 subscribers in the 
system by the end of the 
year. 



■digital Research To 
Introduce Record-Re- 
trieval System: Digital 
Research (DR) will soon in- 
troduce a record-keeping 
software package called 
BT-80. Basically, it is the 
kernel for a data-base man- 
agement system. DR has 
also indicated that it is 
"taking a hard look at 
possibly implementing 
CP/M, MP/M, and PL/I on 
68000 and Z8000 systems." 
Further, they have pur- 
chased a Digital Equipment 
Corporation VAX machine. 
Although this machine is 
primarily intended to keep 
track of their internal opera- 
tions, it will be using the 
UNIX operating system. 
Does this mean that DR 
might be taking a close look 



at UNIX? After all, several 
DR staffers have strong 
UNIX backgrounds. 

Digital Research has also 
disclosed that it is consider- 
ing the possibility of devel- 
oping a software interface 
between CP/NET and the 
EtherNet systems. 



I he Microprocessor 
Catch-22: Intel is currently 
the only supplier of the 8088 
microprocessor (which is ac- 
tually a 16-bit 8086 with 8-bit 
input and output). Most 
designers tend to avoid a 
part that is not "second- 
sourced." In other words, 
they want to be able to get 
the part from another source 
if their primary source has 
delivery problems. Mostek 
has said that it is interested 
in second-sourcing the 8088 
if demand warrants. My 
question is, how is the de- 
mand to materialize while 
waiting for a second-source 
to enter the marketplace? 



R 



andom Bits And 
Random Rumors: The 

EtherNet's specifications 
have been finalized and 
published. If you would like 
a copy, contactthe EtherNet 
Literature department at 
either Xerox, Intel, or Digital 
Equipment Corporation.... 
NEC is about to introduce a 
low-cost version of its Spin- 
writer word-processing 
printer. This new machine 
will sell for $1400 (in lots of 
100) and it will also be used 
with a new NEC microcom- 
puter system rumored for in- 
troduction later this year.... 
It is being whispered that Ep- 
son America Inc, Torrance, 
California, will soon unveil a 
low-cost daisy-wheel 
printer... Ontrax Corpora- 
tion, Sunnyvale, California, 
plans to introduce a 
116-megabyte 8-inch Win- 
chester disk drive soon.... 
Before long, General Instru- 
ment will place on the 
market a speech-synthesis 
chip set in the $5 price range 
for large volumes. The set 
will include the controller, 
32 K bytes or 128 K bytes of 
ROM and speech modules. ... 



214 February 1981 © BYTE Publications Inc 



DG: Realizing the H8's Potential 

For the Engineer; Businessman; and Serious Hobbyist. 



NEW! DG-64D5 Now Available 

Uses Single 5 Volt Supply DYNAMIC RAMS. 
Like our DG-64D, asynchronous refresh 
maintains memory contents during extended 
wait states. Call for additional information. 

Powerful, Bank Selectable 
64K RAM 

Our high capacity, low power DG-64D 64K 
RAM allows more efficient utilization of space, 
freeing your motherboard for peripheral 
interfacing. 

Now 4MHz Operation 

The DG-ADP4 allows for operation of the 
DG-80 CPU at 4MHz while maintaining 
compatibility with the H1 7 Disk System. 
Execution time of CPU intensive programs is 
reduced to half even before utilizing the 
enhanced Z80 instruction set. 



Now Use Standard CP/M® 
Software 

DG's system enhancements provide for RAM 
in Low Memory allowing the use of the widely 
accepted STANDARD CP/M. 

Now Operation in Powerful 
Z80®Code 

Our DG-80 Z80 R based CPU opens a new 
world of more powerful AND efficient 
languages and software. 

Increased Flexibility With New 
Monitor 

DG's FP8 monitor allows front panel debugging 
of 8080 AND Z80 machine language programs 
in either hexadecimal or octal format. Maintains 
all PAM-8 R entry points ancTfeatu res. All 
register sets available. 



The DG system enhancements for the Heath H8 computer are definitely a 
step above in price, performance, and factory support. 



THE DG-80 ZILOG Z80®BASED CPU — $249.00 (Documentation Only $25.00) 



FEATURES: 

• Compatible with Heath* H8 hardware and software 

• Z80CPU — Enhanced instruction set • Provisions for 
up to 8KR0M/EPR0M and/or 4K RAM • Jump-On-Re- 
set to any 1K boundary • DIP switch selectable wait 



states for any or all 8K blocks of memory • All Z80 
interrupt response modes available • Interrupt Acknow- 
ledge and Dynamic Memory Refresh signals available on 
bus • Frequently selected options by DIP switch or sol- 
derless jumper • Machined contact gold sockets for 



R0M/EPR0M. RAM • Includes many advanced features 
for future expansion • Assembled, tested and guaran- 
teed • Extensive operations manual and Z80 PROGRAM- 
MING MANUAL 

90 DAY WARRANTY 



DG-64D 
BEST RAM EVER 
AVAILABLE FOR 

THE H8. 



NEW! 5 VOLT ONLY VERSION 64K RAM — DG-64D5 

Uses Single Supply 5 Volt Dynamic RAMS. Call for further information. 
FEATURES: 



• Up to 64K bytes capacity Dynamic RAM 

• Hardware bank selectable in 8K incre- 
ments • Software bank selectable in 16K 
increments through I/O port • On-board 
bank select/CPU ROM disable port, address- 



able to any of 256 I/O addresses • Up to 8 
boards controllable through one I/O port 
(allows page mode operation) • On-board 
transparent refresh for 8080 or Z80 
microprocessor backed up by asynchronous 



refresh which maintains memory contents 
during extended wait states • 4 MHz opera- 
tion with no wait states required • Low 
power consumption — less than 8 watts 
• Assembled, tested, & burned-in • 90 
DAY WARRANTY • 64K-S529.00; 48K- 
$480.00; 32K-S431.00; 16K-S382.00; 
0K-S333.OO; Documentation 0nly-$15.00 



DG-FP8 — $69.95 



Monitor/Utility package for DG-80 CPU provides 
functions of PAM-8 as well as the following: 



• Split Octal or Hexidecimal Entry and Dis- 
play • Z80 monitor features such as dis- 
play alternate register sets, display index 
registers, • "Shorthand" display of mem- 
ory contents pointed to by general purpose 
Documentation Only - $15.00 (Source Listing Not Included) 



registers • Supports STANDARD CP/M 
provided by D-G as well as HDOS • Pro- 
vides firmware support for DG-ADP4, 4 MHz 
hardware • Includes single step features 



DG-ADP4 — $19.95 



Plug-in hardware modification to allow operation of the Heath" H17 disk system with the 
DG-80at4 MHz. Requires the use of the DG-FP8 firmware package. 



16K CHIP SETS $49.00 

(8-4116 Type Dynamic RAMS) for DG- 32O.0G-64O,Apple".TRS-80" 
H88/89".andPef 



DG-CMD1 — $29.95 



ROM disable port for use with the 
Heath* H8 computer. Addressable to 
any of 256 I/O ports. Allows the use of a 
full 64K of RAM when used in conjunc- 



tion with the DG-80 CPU and the DG-FP8 
hardware/firmware package (NOT RE- 
QUI RED FOR SYSTEMS UTILIZING THE 
DG-64D MEMORY BOARD) 



DG-FP8/DG-ADP4 - TOGETHER - $79.95 

Save on Combination Purchase — Reg. $89.90 



DG-32D — 32K — $339.00 — 16K — $287.00 
— tfK — $235.00 -DOCUMENTATION $12.00 



STANDARD CP/M Ver 2.2 $130.00 



CP/M is a registered trademark of Digital Research of Pacific Grove. California. Heath. HDOS. H 8, H88/89 & PAM8 are registered trademarks ofthe Heath Company, Z80isa registered trademark of Zilog 
Corp. PET is a registered trademark of Commodore. Apple is a registered trademark of Apple Computer TRS-80 is a registered trademark of TANDY Corp, 



n-B 



Ordering Information: Products listed available from DG Electronic 
Developments Co., P.O. Box 1124, 1827 South Armstron, Denison, Tx. 
75020. Check, Money Order, VISA or Master Charge accepted Phone 
orders (charge only) call (214) 465-7805. No COO's. Freight prepaid. 
Allow 3 weeks for personal checks to clear. Texas residents add 5%. 
Foreign orders add 30%. Prices subject to change without notice. 



Circle 147 on inquiry card. 



BYTE February 1981 



215 



BYTELINES __ 

Hewlett-Packard is about to 
set forth a single-board 
microprocessor version of its 
1000-L computer to compete 
with the Digital Equipment 
Corporation LSI-11.... Con- 
trol Data plans to introduce 
a self-contained PLATO sys- 
tem. The PLATO system is 
currently a mainframe-based 
system that includes remote 
terminals with high-resolu- 
tion graphics and an exten- 
sive library of interactive 
educational software... 
Shugart Associates, the cur- 
rent leader in floppy-disk 
drives, is rumored to be de- 
veloping an optical disk- 
storage system. The basic 
technology for this system 
was developed by Shugart's 
parent organization, Xerox, 
and Thompson-CSF..., 



■ Irst Xenlx/Z8001 
System Announced: Tri- 

Data Systems, City of In- 
dustry, California, is the first 
company to announce a 
microcomputer system using 
the Zilog Z8001 and Micro- 
soft's Xenix operating sys- 
tem. The Z8001 employs 
segmented rather than direct 
addressing. This desk-top 
system, called the SST, con- 
tains a Z8010 memory-man- 
agement integrated circuit 
that dynamically relocates 



code and protects memory 
areas. The SST utilizes a ten- 
slot motherboard for mem- 
ory expansion in 128K-byte 
modules. 



w, 



III Microcomputers 
Leapfrog Over Minicom- 
puters and Mainframes? 

The newer 16- and 32-bit 
microprocessors, soon to be 
sampled by integrated- 
circuit manufacturers, will 
contain some new and 
sophisticated features. For 
example, the forthcoming 
NS16000' 16-bit micropro- 
cessor from National Semi- 
conductor and the iAPX-432 
microcomputer from Intel 
will both have true virtual 
memory capability that will 
allow very large memory 
systems. Sixteen-bit micro- 
computers like the 8086, 
Z8000, and 68000 do not 
lend themselves to virtual 
memory systems. Intel, how- 
ever, says that it expects to 
have an 8086 with virtual 
memory later this year. 

Virtual memory requires 
the microprocessor to stop 
in the middle of an instruc- 
tion if it determines that the 
address called is not in mem- 
ory, back up execution of 
the instruction, and restart 
the instruction after the con- 
tents of that virtual address 
have been brought in from a 



mass-storage device (eg: a 
hard disk). 

Returning to the original 
question, experts concede 
that, simply because micro- 
computers now have fea- 
tures once found only in 
larger machines, it does not 
follow that they will over- 
take minicomputers and 
maxicomputers. Each year 
the minicomputers and 
maxicomputers add perfor- 
mance features that keep 
their power far ahead of 
microcomputers. In fact, the 
new more powerful micro- 
computers now have fea- 
tures that were found in 
larger systems five or more 
years ago. 



R, 



,obot Kit An- 
nounced: In the December 
1979 BYTE News, I predicted 
that a robot kit would be in- 
troduced in 1980. It now 
seems as if that prediction 
will come true in 1982. 
Heath Company recently de- 
monstrated a 3-foot-high 
robot prototype to Heath 
retailers that it plans to in- 
troduce in 1982. The robot 
kit will use the Motorola 
6802 microprocessor with 
4 K bytes of programmable 
memory and 32 K bytes of 
ROM (read-only memory). It 
will have a detachable 



joystick, voice synthesis, 
and one multipurpose arm. 
At this time, it is projected 
that the kit will cost less 
than $1000. 



Whange Of Name: 

Seagate Technology is the 
new name for Shugart Tech- 
nology. Seagate Technology 
is the Scotts Valley, Califor- 
nia, firm that manufactures 
Winchester-technology 
5'/ -inch hard-disk drives. 
The decision to change its 
name was made by Seagate 
Technology to help 
distinguish it from the 
famous maker of floppy-disk 
drives, Shugart Associates. 
Both companies were found- 
ed by David Shugart. How- 
ever, Mr Shugart is no longer 
affiliated with Shugart 
Associates. 



MAIL: I receive a large 
number of letters each month 
as a result of this column. If you 
wish a response, please include 
a stamped, self-addressed 
envelope. 

Sol Libes 
POB 1 992 
Mountainside NJ 07092 



LET YOUR APPLE SEE THE WORLD! 



The DS-65 Diglsector" is a random access video digitizer 
which converts a TV camera's output Into digital Infor- 
mation the Apple can process. It features 256 X 256 
resolution with up to 64 levels of grey scale 
Scanning sequences are user programmable. 
On-board software in EPROM is provided for 
displaying digitized Images on the Hi-Res 
screen. 

Use the DS-65 for: Precision Security Systems 
• Computer Portraiture • Robotics • Fast to 
Slow Scan Conversion • Moving Target Indi- 
cators • Reading UPC codes, schematics, musi 
cal scores and paper tape • 




TH ft&D®D^§> 



DS-65 Price: $349.95 
FSII Camera Price: $299.00 
Combination Price: $599.00 



NEW SOFTWARE FOR THE DS-65 IS NOW AVAILABLE 
ON DISK! 



— Portrait System Software:This program includes 
captions and a credit line, reverse printing for 
T-shirt application and the option to save por- 
traits on disk. 

— Picture Scanner: Provides a variety of differ- 
ent dithering algorythms for compressing the 
digitized Image into the Hi-Res screen. 

Write or call for more Information! 



GIVE YOUR APPLE THE GIFT OF SIGHT! 

Master Charge / Visa Accepted 



M® [SUSS 3 RO. BOX 111 DEL MAR, CA 9201 4 71 4-942-2400 



216 February 1981 © BYTE Publications Inc 



Circle 148 on inquiry card. 



This 

printer 

costs less 

than $450. 

Beat that... 

if you can. 




Epson 



This is the Epson MX-70. The lowest priced dot 
matrix printer you can buy. Now, that in itself 
should make it very attractive to a lot of people. 
But you ain't heard the half of it. 

To begin with, the MX-70 has a lot more in 
common with our now-famous MX-80 than just 
the name. Like unequalled Epson reliability. 
And technological breakthroughs like the 
world's first disposable print head. But frankly, 
the MX-80 packs a lot more power than some 
people need. So we built the 
MX-70 to be a no-frills print- 
er. At a no-frills price. 

But the MX-70 is still a great 
little printer. We give you 
80CPS unidirectional print- 
ing. Top-of-form recognition. 
Programmable line feed and 
form lengths. Plain paper 
printing. An easy-to-read 5x7 
matrix. Self test. And an 
adjustable tractor feed. 

That's what you'd expect 




from a basic little printer. But here's something 
you wouldn't expect: the finest graphics package 
on the market today. Free. 

We call it GRAFTR AX II. And it means 480 dots 
across the page, resolution to 60 dots per inch, 
and a graphic image free of the jitter and overlap 
that plagues other printers. You get cleaner grays 
and finer point resolution. 

So now you've got a choice. You want more 
power and extra functions, you buy the MX-80. 
You want a basic little printer 
that prints, and keeps on 
printing, you buy the MX-70. 
They're both at your dealer 
now. 

But at this price, you'd bet- 
ter hurry. 

EPSON 

EPSON AMERICA, INC. 



23844 Hawthorne Boulevard • Torrance, California 90505- (213) 378-2220 



Circle 149 on Inquiry card. 



BYTE February 1981 



217 



H 



CQMPuTTRQNICS 



N 
C. 



... EVERY THING FOR YOUR TRS-80 ••• 



* TRS-80" is a trademark of the Radio Shack Division of Tandy Corporation 



****** >*-*** 

MOD-II PROGRAMS 



* All orders processed within 24-Hours 
•k 30-Day money back guarantee on all TRSDOS Software 
•k Add $2.00 for shipping in UPS Areas 
• Add $3.00 for C.O.D. or NON-UPS Areas 
• Add $4.00 outside U.S.A., Canada & Mexico 
•k We will match any bonafide advertised price 
in any of the Major Computer Magazines 



A 

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(1) ELECTRIC PENCIL (Michael Shrayer Software)... 
Complete word processor with extensive editing and 

printer tormatting features $325 (STANDARD 

TRSDOS VERSION). ..$350 (DIABLO, NEC OR QUME 
TRSDOS VERSION). 

(2) GENERAL LEDGER, ACCOUNTS RECEIVABLE, 
ACCOUNTS PAYABLE, INVENTORY CONTROL, 
INVOICING AND PAYROLL (Small BusinessSystems 
Group) ...an extensive businesssystem for the serious 
user.. .can be used one module at a time or as a co- 
ordinated system. ..$225. per module. ..$1299 for the 
complete system. 

(3) GENERAL LEDGER, ACCOUNTS RECEIVABLE, 
ACCOUNTS PAYABLE, INVENTORY CONTROL 
AND PAYROLL (Compumax) ...a complete user ori- 
ented business system ...can be used one module at a 
time or as a coordinated system... $140 per module... 
$995 for the complete system. 

(4) MOD-II UTILITY PACKAGE (Racet Computes)... 
adds important utilities to TRSDOS. ..copy files 
selectively... faster and more accurate file copying... 
repair bad directories.. .displays sorted directory of 
all files on 1 to 4 disk drives... SUPERZAP... change 
disk IO...and more... $150. 

(5) ADVENTURE #1-#9 (Scott Adams - Adventure 
International). ..a series of games formally only 
available on the large computers... your goal is to work 
your way through a maze of obstacles in order to 
recover a secret treasure or complete a mission.. .the 
package includes all 9 Adventures written by Scott 
Adams.. $99.95. 

(6) GSF (Racet Computers). ..Generalized Subroutine 
Facility...a series of super fast machine language 
utilities that can be called from a BASIC program (no 
machine language knowledge required). ..sorts 1000 
items in under 5 seconds. ..allows PEEK and POKE 
statements.. .move data blocks.. .compress and un- 
compress data., works under TRSDOS.. $50. 

(7) DSM (Racet Computes) ... Disk Sort Merge ..sorts 
and merges large multiple diskette files on a 1 to 4 
drive system...NOT AN IN MEMORY SORT ...can 
actually alphabetize (or any other type of sort) 4 disk 
drives worth of data., sorts one complete disk of 
information in 10 minutes...information is provided to 
use DSM with the RS MAILING PROGRAM ...works 
under TRSDOS...$150. 

(8) RSM (Small Systems Software) ...a machine 
language monitor and disassembler.. .can be used to 
see and modify memory or disk sectors. ..contains all 
the commands found on the Model-I version plus 
some additional commands for the MOD-II. ..works 
under TRSDOS...$39.95. 

(9) BLINK BASIC LINK FACILITY (Racet Computes).. 
Link from one BASIC program to another saving all 
variables.. .chain programs without losing variables 
...$50. 

(10) BASIC CROSS REFERENCE UTILITY (Racet 
Computes)., lists all variables and strings used in a 
program (with the line numbers in which they appear) 
...lists all GOTO's and GOSUB's (with the line num- 
bers in which they appear) ..searches for any specific 
variables or strings (with the line number in which 
they appear) ..$50 

(1 1) DEVELOPMENT PACKAGE (Racet Computes)... 
SUPERZAP (to see, print or change any byte on a 
diskette)... Disassembler and MOD-II interface to the 



MICROSOFT EDITOR ASSEMBLER PLUS including 
uploading services and patches for Disk I/O. .assemble 
directly into memory.. .save all or portions of source 
to disk., dynamic debug facility (ZBUG)...entended 
editor commands.. .$125. 

(12) HARD/SOFT DISK SYSTEM (Racet Computes)... 
The software essential to inte face any of the popular 
large hard disk drives... completely compatible with 
your existing software and files.. .allows up to 20 
megabytes ofstorage (and larger). ..directory expand- 
able to handle thousands of files ...$400. 

(13) CAMEO HARD DISK DRIVE CONTROLLER 
coming soon (November 1?) 

(14) HARD DISK DRIVES...coming soon (Nov. 1?). 

(15) HIE COMPUTRONICS, INC. SHARE-A- 
PROGRAM DISKETTE #1...works under TRSDOS...a 
collection of programs written by MOD-II owners. . 
programs include data base management... a word 
processor. mail system ...mortgage calculations... 
checkbook register.. .and many others. ..$8 (add $3 
postage outside of the United States, Canada and 
Mexico). ..FREE if you send us a diskette containing 
a program that can be added to the SHARE-A-PRO- 
GRAM DISKETTE. 

(16) WABASH CERTIFIED DISKETTES ..$39.95 (per 
box of 10). 

(17) FLIP SORT DISKETTE STORAGE TRAY ..Stores 
50 diskettes, .comes complete with index-dividers, tilt 
plates and adjustable spacing.. .$44.95. 

(18) MASTER PAC 100... 100 essential programs. . 
BUSINESS.. .PERSONAL FINANCE ..STATISTICS... 
MATH...GAMBLING...GAMES... includes 125 page 
manual and 2 diskettes. ..$99.95. 

(19) BUSINESS PAC 100... 100 essential business 
programs... INVENTORY CONTROL. PAYROLL- 
BOOKKEEPING SYSTEM...STOCK CALCULA- 
TIONS... CHECKBOOK MAINTENANCE. ..AC- 
COUNTS RECEIVABLE-ACCOUNTS PAYABLE... 
includes 125 page manualancltwodiskettes... $149.95. 

(20) EDITOR ASSEMBLER (Galactic Software Ltd.).., 
the first user oriented Editor Assembler for the 
MODEL II and was designed to utilize all the features 
of the MODEL II It includes innovative features for 
ease of coding and debugging and complete docu- 
mentation (over 120 pages) ...works under TRSDOS 
...$229.00. 

(21) BASIC COMPILER (Microsoft)... changes your 
source programs into machine language ...increases 
program execution by 3-10 times.. .$395. 

(22) MAIL/FILE SYSTEM from Galactic Software Ltd. 
stores 2,500 names per disk. No sorting time is 
required since the file is automatically sorted by first 
and last name plus Zip Code on input. Retrieve byany 
combination of 19 user codes Supports an 11 digit 
alphanumerica Zip. Supports a message line. Comes 
complete with user-oriented documentation (100- 
page manual). Allows for company name and individ- 
ual of a company and complete phone number (and 
extension), works under TRSDOS. .$199.00 

(23) INCOME TAX PAC... Professional income tax 
package... most forms and schedules ..output to video 
or line printer.. automatic memory storage of all 
information. ..data can be loaded from diskette, 
changed and edited ...built in error checking . $199.95. 

(24) COMPUTER GAMES (SBSG)...Mean Checker 
Machine, Star-Trek III, Concentration, Treasure Hunt. 
Banco, Dog Star Adventure. ..$74. 95. 



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(1) CP/M (Lifeboat Associates) an alternative 

operating system for the MOD-II that allows MOD-II 
owners to use any of the hundreds of programs 
available under CP/M. ..$170. 

(2) CP/M HANDBOOK (Sybex) a step-by-step 
guide to CP/M... takes the reader through each of the 
CP/M commands...numberous sample programs... 
practical hints. reference tables.. .$13.95. 

(3) GENERAL LEDGER, ACCOUNTS RECEIVABLE, 
ACCOUNTS PAYABLE, INVENTORY CONTROL, 

AND PAYROLL (Peachtree Software)., requires CP/M 
and MICROSOFT BASIC. ..professional business 
systems. ..turn key operation ...can be used as single 
modules or as a coordinated system.. .$500 per 
module. ..$2500 for the complete system. 

(4) WORD-STAR... The ultimate word processor ..a 
menu driven word processing system that can be used 
with any printer. All standard word processing 
commands are included ...plus many unique com- 
mands only found on WORD STAR. ..requires CP/M 
...$495. 

(5) MAIL LIST MERGE ...An add on package that 
allows the user to send form letters (created on 

I WORD-STAR) to any compiled mailing list (using any 
CP/M based MAIL program such as the PEACHTREE 
MAIL PROGRAM).. requiresCP/M, WORDSTAR and 
andy CP/M based mail program. ..$150 

(6) SELECTOR 111 (Micro-Ap) ...complete data 
management system. ..userdefined fields and codes... 
manages any list defined by the user., includes 
additional modules for simplified inventory control, 
accounts receivable and accounts payable. ..requires 

I CBASIC-2...S295. 

(7) SELECTOR IV (Micro-Ap)...the ultimate data 
management system. ..all features use the SELECTOR 
III plus.. .data file format conversions., full page report 
formatter.. . computations. .global search and replace 
...hard disk compatible., data/text merging.. .$550 

(8) GLECTOR (Micro-Ap).. add on package to the 
SELECTOR., general ledger that allows the user to 
define a customized chart of accounts . $350. 

(9) C8ASIC-2 a non-intesactive BASIC used for 
many programs that run under CP/M... allows user to 
make more efficient use of disk files... eliminates the 
use of most line number references.. .require on such 
programs as the SELECTOR.. .$120, 

(10) MICROSOFT BASIC. ..an enhanced version of the 
MICROSOFT BASIC found on TRSDOS ...adds 
commands such as chaining (allows the user to LOAD 
and RUN a new program without losing the variables 
currently in memory), .long variable length file 
records. WHILE/WEND and others... can be used with 
the BASIC COMPILER to speed up programs (3-10 
times faster execution). ..$325. 

(11) MASTER TAX (CPAids) ...professional tax 
preparation program., prepares schedules, A. B. C. D, 
E, F, G, R/RP. SE. TC. ES and forms 2106. 2119. 2210. 
3468, 3903. 2441. 4625, 4726. 4797. 4972. 5695 and 
6521. Printing can be on readily available pre-printed 
continuous forms, on overlays, or on computer 
generated IRS approved forms. Maintains dint history 
files.. .interactive with CP/Aic!s General Ledger... $995. 

(12) GENERAL LEDGER II (CP Aids) ...designed for 
CPA's... stores complete 12 month detailed history of 
transactions. ..generates financial statements, 
depreciation, loan amortizations, journals, trial 
balances, statements of changes in financial position, 
and compilation letters.. .includes payroll systemwith 
automating posting to general ledgers. ..prints 
payroll register, W2"s and payroll checks. .$450. 

(13) ELECTRIC PENCIL (Michael Shrayer Software) 
...Complete word processor with extensive editing 
and printer formatting features.. .$275 (Standard 
printer version)...$300 (DIABLO. NEC or QUME 
version). 

(14) BASIC COMPILER (Microsoft) .changes your 
source programs into machine language. ..increases 
program execution by 3-10 times. ..5395. 



(CP/M IS A REGISTERED TRADEMARK 
OF DIGITAL RESEARCH) 



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A COMPLETE INCOME TAX PROGRAM (LONG AND SHORT FORM) 

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BYTE February 1981 219 



Image Processing 
With a Printer 



Clark A Calkins 
2564 Walnut Blvd #106 
Walnut Creek CA 94598 



For a long time I have been inter- 
ested in producing recognizable im- 
ages using a basic Teletype just as you 
see in many computer stores; and I 
thought that an expensive camera and 
interface were required to digitize the 
picture. But in 1979 an article in Dr 
Dobb's Journal described just how to 
do this type of image processing with 
a Diablo printer. (See reference 1.) 
While I didn't have this type of 
printer, I figured the concept should 
work with my Model 43 Teletype or 
any other printer. After all, the hard- 
ware interface required looked simple 
enough. What could I lose? I worked 
out my ideas, implemented the 
system, and now I can process images 
inexpensively at home. So as a suc- 
cessful personal-computer experi- 
menter, I'll pass on my experience to 
you. 

An Overview of the System 

The principle behind this image 
processing system is easy to under- 
stand and implement in a home com- 
puter system. The procedure used to 



About the Author 

Clark A Calkins has worked for 11 years 
with the General Electric Company at the 
Vallecitos Nuclear Research Center and now 
holds a position as a systems programmer for 
the Advanced Nuclear Applications Group. 



prepare a digital picture contains the 
following steps: 

• Connect a light-sensitive device 
(such as a phototransistor) to the in- 
put of an A/D (analog-to-digital) 
converter that is connected to the 
computer. 

• Mount the phototransistor on the 
print head of the printer so that it 
senses light reflected off the paper in 
the printer's print position. 

• Place the paper containing the 
image in the printer so the print head 
will traverse the image; then send a 
series of space characters to the 
printer to cause the print head to 
move across the paper. 

• Measure and store the values of 
light intensity at each character posi- 
tion under program control, using 
A/D-converter output. 

• Insert a blank sheet of paper into 
the printer. 

• Use a computer program to print 
selected characters onto the blank 
sheet; each character corresponds to 
the light intensity at a given print 
position. The higher the intensity, the 
lighter the character should be. 

Having decided that this would be 
an interesting project, I went to the 
local electronics store and purchased 
the necessary parts and assembled the 
unit. When I loaded in a sample con- 
trol program written in BASIC, the 



thing actually worked, and after a lit- 
tle experimentation, I could even 
recognize some features! Then the fun 
started, I cut pictures from the maga- 
zines lying around the house and 
started to process them while trying 
different substitution characters. This 
was great fun for my entire family! 

After a few hours of playing with 
this system, I started to realize that I 
needed a better control program that 
would execute faster. The BASIC 
program worked at about three char- 
acters per second, but with a faster 
program, I could try larger pictures. 
The basic functions required were: 

• Scan over a variable-width image 
of any reasonable length at a much 
faster speed. 

• Save the resulting digital data out 
on a disk file for later use. 

• Be able to use a user-defined char- 
acter-substitution sequence (the more 
flexible, the better). 

The results of this effort are shown 
in listing 1. Here is a control program 
written for the CP/M (version 1.4) 
operating system that does what is re- 
quired (and a little more). It can scan 
a line of up to 255 characters and as 
many as 255 lines (memory permit- 
ting). The character-substitution se- 
quence is limited to sixty-four char- 



220 February 1981 © BYTE Publications Inc 



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Figure 1: The image reproduced by IMAGE was originally a black-and-white photograph. The analog-to-digital converter used by 
the author registered a dark-to-light difference of 130, when the picture was processed. Magazine and book photos or artwork can 
also be reproduced satisfactorily. 

February 1981 © BYTE Publications Iik 221 



F = 


file the data. 






H = 


help, display menu. 






M = 


set maximum and minimum values. 


P = 


print the data back 


out. 




Q = 


quit and return to CP/M. 




R = 


read the file in. 






S = 


scan a new page. 






T = 


set the tone array. 






Table 1: The menu 


displayed 


by 


IMAGE. 







acters, and there is a primary and 
secondary string. Two separate 
strings were chosen so the printer 
would not have to backspace to pro- 
vide overstrike capability; characters 
from the secondary string print on 
top of those from the primary string. 
However, it does have to return the 
carriage without feeding a line. 

For an example of what a user can 
do with this system, refer to figure 1. 
In order to achieve the desired con- 
trast, it was necessary to use over- 
strike on the darker areas. This pic- 
ture originally was a black-and-white 
photograph reproduced from a maga- 
zine page. The difference between the 
maximum and minimum values read 
from the A/D converter for this pic- 
ture, was decimal 130. The higher this 
difference is, the more contrast the 
resulting printout will have and the 
better it will look. 

Using IMAGE 

The image processing program, 
IMAGE, is run as a transient program 
under Digital Research's CP/M 
operating system. If IMAGE is being 
used under some other system, the 
start-up procedure would change. 
The program is initially executed by 
typing in the following command 
line: 

A> IMAGE filename 

In this case, the data-storage file is 
identified as "filename. img". (The ex- 
tension "img" is assumed by the pro- 
gram.) This will be used for all corres- 
pondence with the disk. When con- 
trol is transferred to this program, a 
heading and initial menu are dis- 
played, allowing the user to choose 
one of several options. (See table 1.) 
The user may type either F, H, M, P, 
Q, R, S, or T (uppercase or lower- 
case). Anything else is ignored and 
causes the full list to be printed. 

F: File the Data 

This writes out the data that was 

Text continued on page 240 



Listing 1: IMAGE, the control program for image processing. This version is written 
for CP/M version 1.4 (compatible with version 2.0) and can scan 255 lines of up to 255 
characters. Overstrike capability is provided to increase contrast of output pictures by 
darkening areas as necessary. Try squinting your eyes or holding the images at different 
viewing distances to obtain a maximum of picture clarity (ie: the illusion's gestalt). 



IMAGE. ASM NOVEMBER 4,1979 

COPYRIGHT 1979, CLARK A. CALKINS 



THIS PROGRAM ALLOUES A USER TO SCAN OVER AN IMAGE PLACED IN 
THE CP/M LIST DEVICE AND RECORD THE RELATIVE GRAPHIC DENSITY 
VIA AN A/D. IT IS ASSUMED THAT THE USER HAS PLACED A PHOTO 
SENSITIVE DEVICE ON THE HEAD OF THE PRINTER AND CAN READ 
THE RELATIVE ENTENSITY OVER AN A/D CHANNEL. REFER TO DR. 
DOBBS JOURNAL, OCTOBER 1979 (VOL 4, ISSUE 9, H39) FOR DETAILS 
ON DOING THIS. 

TO USE THIS PROGRAM, TYPE: 
AHHAGE FILENAME<RET> 

ONCE EXECUTING, THIS PROGRAM UILL ASK FOR THE OPTION THAT 
IS DESIRED. THE USER MAY; 

1) SCAN A NEU IMAGE AND RECORD THE DENSITY DATA, 

2) FILE THE EXISTING DATA AUAY ON THE FILE SPECIFIED, 

3) READ IN DATA FROM A PREVIOUSLY SAVED SCAN FROM THE 
SPECIFIED FILE, 

4) SET THE TONE ARRAYS THAT UILL BE USED TO PRINT BACK THE 
IMAGE TO ANY DESIRED SET OF CHARACTERS, 

5) PRINT OUT THE IMAGE USING THE CURRENT TONE ARRAYS, 

6) SET MAXIMUM AND MINIMUM VALUES. 

THE FILE NAME SPECIFIED UILL BE GIVEN THE DEFAULT EXTENSION 
OF 'IMG'AND THIS MUST EXIST IF DATA IS TO BE READ BACK IN, OR 
IT UILL BE CREATED (IF NECESSARY) IF NEU DATA IS TO BE FILED 
AUAY. TO SCAN A NEU IMAGE, THIS CODE UILL ASK FOR THE DESIRED 
LINE LENGTH. TYPE IN THE LENGTH (IN DECIMAL) AND THEN YOU UILL 
BE GIVEN THE OPPORTUNITY TO POSITION THE PAPER BEFORE THE SCAN 
STARTS. ONCE STARTED, THE SCAN UILL CONTINUE UNTIL 2SS LINES 
HAVE BEEN SCANNED OR THE USER HAS TYPE ANY KEY (ONLY CHECKED 
AT THE END OF A LINE). THE RANGE OF VALUES READ UILL BE GIVEN 
AND CONTROL UILL RETURN TO THE OPTION SELECTION LEVEL. UHEN 
PRINTING THE DATA BACK OUT, TYPING ANY KEY (AGAIN AT THE END 
OF A LINE) UILL HALT THE PROCESS AND RETURN TO THE OPTION 
SELECTION LEVEL. 

THIS PROGRAM UILL NOT CHECK MEMORY USAGE, SO BE SURE THAT 
THERE IS ENOUGH ROOM FOR THE IMAGE BEING SCANNED (ONE BYTE 
IS USED PER COLUMN POSITION, PER LINE. 



0100 




ORG 


100H 




0100 31D307 


IMAGE 


LXI 


SP, STACK 


JSETUP STACK 


0103 117C04 




LXI 


D, HELLO 




0106 0E09 




HVI 


C,9 




0108 CD0S00 




CALL 


CPM 




010B 216500 




LXI 


H,005CH+9 


JSET IMAGE EXTENSION TO 


010E 3649 




HVI 


H,'I' 




0110 23 




INX 


H 




0111 364D 




MVI 


H,'H' 




0113 23 




INX 


H 




0114 3647 




MVI 


M,'G' 





'IMG'. 



0116 11BS04 


OPT 


LXI 


0119 OE09 




MVI 


011B CD0S00 




CALL 


011E 118105 


UHAT 


LXI 


0121 CDF303 




CALL 


0124 E65F 




ANI 


0126 FE46 




CPI 



ASK FOR THE DESIRED OPTION. HERE UE DON'T UAIT FOR A CARRIAGE 
RETURN, JUST THE FIRST THING TYPED. INVALID RESP0NCES ARE 
IGNORED. 



D,0PTI0N;UHAT DOES THE USER UANT TO DO? 

C,9 

CPM 

D,QUESTN 

ASK 

5FH ;MAKE UPPER CASE FOR COMPARISONS. 

'F' ;FILE THE DATA? 

Listing 1 continued on page 224 



222 February 1981 © BYTE Publications Inc 



Circle 151 on inquiry card. 



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Please send the items checked below: 
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G JAWS 16K RAM fully ammblid, tested, burned in, 

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eny of the above in 16K blocks up to 64K. No. 16EXP, 

S129.95* 

*AII prices plusS 2 postage and handling. Connecticut 
residents add sales tax. 
Total enclosed: S. 



CI Personal Check G Money order or Cashiers Check 

G VISA G MASTER CHARGE (Bank No ) 

Acct. No. Exp. Dete 

Signature 

Print Name 

Address — 

City 

State 



G Send me more information 



_Zip. 



Listing 1 continued: 








0128 CAA302 


JZ 


FILE 




012B FE50 


CPI 


'?' 


JPRINT THE FILE 


012D CA0502 


JZ 


PRT 




0130 FE54 


CPI 


'T' 


JSET THE TONES 


0132 CA5A03 


JZ 


TSET 




0135 FE53 


CPI 


''S' 


;SCAN A NEU PACE 


0137 CA4C01 


JZ 


SCAN 




013A FES1 


CPI 


'Q' 


•QUIT PR0CESSIN6 


013C CA0000 


JZ 







013F FE52 


CPI 


'R' 


;read in the file? 


0141 CA0F03 


JZ 


READF 




0144 FE4D 


CPI 


*N' 


•SET HAX AND HINS 


0146 CA7D03 


JZ 


SETKAX 




014? C31601 


JMP 


OPT 


;N0T RECOGNIZED 



014C 


AF 


014D 


32D307 


0150 


3D 


0151 


32D407 


0154 


111D06 


0157 


OE09 


0159 


CD0500 


015C 


CD9C03 


015F 


32D507 


0162 


1E0D 


0164 


CD0A04 


0167 


11?F05 


016A 


CDF303 


016D 


1604 


016F 


3E01 


0171 


320807 


0174 


OEFF 


0176 


21D707 


017? 


3AD507 


017C 


47 


017D 


CDCF03 


0180 


77 


0181 


3AD307 


0184 


BE 


0185 


D28C01 


0188 


7E 


018? 


32D307 


018C 


3AD407 


018F 


BE 


1 90 


DA9701 


1 93 


7E 


1 94 


32D407 


1 97 


23 


1 98 


14 


0199 


F2A501 


019C 


3A0807 


019F 


3C 


01A0 


320807 


01A3 


1600 


01A5 


1E20 


01A7 


CD0A04 


01AA 


05 


01AB 


C27D01 


01AE 


1E0D 


01 BO 


CD0AO4 


01B3 


1E0A 


01B5 


CD0A04 


01D8 


CDFD03 


01BB 


DACF01 


1 BE 


D5 



SCAN ACROSS THE PAGE AND COLLECT DATA FROM THE A/D. AT FIRST 
ASK THE USER FOR THE LINE LENGTH TO USE (A DECIMAL NUMBER). 
THEN GIVE HIM/HER AN OPORTUNITY TO POSITION THE PAGE BEFORE 
STARTING. CONTINUE SCANNING UNTIL 255 LINES HAVE BEEN CHECKED 
OR THE USER HAS TYPED A KEY (CHECKED AT THE END OF A LINE 
ONLY). UHEN DONE, REPORT THE MAXIMUM AND MINIMUM VALUES READ 
FROM THE A/D. HE HOPE THAT THE USER HAS ENOUGH MEMORY FOR ALL 
OF THIS SCAN DATA (ONE BYTE PER COLUMN PER LINE) AS A CHECK 
IS NOT MADE (BUT COULD BE IN NECESSARY). 



SCAN 



OUTLP 



INLP 



DOI 



D02 



D03 



XRA 

STA 

DCR 

STA 

LXI 

MVI 

CALL 

CALL 

STA 

MVI 

CALL 

LXI 

CALL 

MVI 

MVI 

STA 

MVI 

LXI 

LDA 

MOV 

CALL 

MOV 

LDA 

CMP 

JNC 

MOV 

STA 

LDA 

CMP 

JC 

MOV 

STA 

INX 

INR 

JP 

LDA 

INR 

STA 

MVI 

MVI 

CALL 

DCR 

JNZ 

MVI 

CALL 

MVI 

CALL 

CALL 

JC 

PUSH 



;set maximum and minimum values 

;find line length from user 



;tell user to ready the paper 
;this is a sector counter 



A 

MAX 

A 

MIN 

D,LLNGTH 

C,9 

CPM 

GETNUM ;GET NUMBER FROM USER 

LNGTH 

E, 13 ;RETURN THE CARRIAGE 

PRINT 

D,P0S 

ASK 

D,4 

A,1 

NSECT 

C,255 ;MAXIMUM ROU COUNT 

H.BUFF ;SET BUFFER ADDRESS 

LNGTH ;C0LUHMN COUNT 

B,A 

READ 

M,A 

MAX 

M 

DOI 

A,M 

MAX 

MIN 

M 

D02 

A,M 

MIN 

H 

D 

D03 

NSECT 

A 

NSECT 

D,0 

W ' 

PRINT 



;get a value from the a/d 

;keep track of max AND MIN VALUES 



jcount bytes 
jsector limit yet? 
;yes, count them 



;move one column 



INLP 

E,13 

PRINT 

E , 1 

PRINT 

CHECK 

TOUT 

D 



;NEXT LINE 



;CHECK THE KEYBOARD 



Listing 1 continued on page 226 



224 February 1981 © BYTE Publications Inc 




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Circle 152 on Inquiry card. 



' MBC Systems, Inc. 

(203) 342-2747 






I ss»"a 




NORTH STAR HORIZON: 

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HRZ-2-32K-Q-Factory ASM$2675 
64K DD or Q Also Available 

HDS-18-F $4449 

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Mail Manager $ 269 

General Leger $ 775 

ACC. REC. OR ACC. PAY..$ 445 

Word Star $ 350 

Medical-Dental SYS $2500 




COMMODORE (PET) : 

2001-32K-BorN Keyboard $1090 
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TI 99/4 ConsoleSMonitor . . $990 
INTERTEC SUPERBRAIN: 



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PRINTERS 

Letter Quality: 

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Dot Matrix: 

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799 $999 

EPSON MX-80 $ 599 

PAPER TIGER 460G $1250 

BASE II MST $ 649 



DISPLAY TERMINALS 

HAZELTINE 1420 $ 949 

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INTERTUBE III $ 775 

TELEVIDEO 920C $ 849 



Since 1977 complete sales and 
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Visa and Master Charge welcome 
Most items shipped by UPS. 

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28 MARLBOROUGH STREET 
PORTLAND, CONN. 06480 

(203)342-2747 TWX 710-428-6345 
k M-F 9-6 SAT. 9:30-3:00 



Listing 1 continued: 



01BF 


110000 


01C2 


IB 


01C3 


E3 


01C4 


E3 


01C5 


7B 


01C6 


B2 


01C7 


C2C201 


01CA 


D1 


1 CB 


0D 


01CC 


C27901 


01CF 


3EFF 


01D1 


91 


01D2 


328607 


01 D5 


OC 


1 D6 


OB 


om? 


0E01 


01 D9 


C40500 


01DC 


214A06 


01 HF 


3AB307 


01E2 


5F 


01E3 


1600 


01ES 


010A03 


01E8 


CB3404 


01EB 


215A0A 


01EE 


3AD407 


01F1 


5F 


01F2 


1600 


01F4 


010A03 


01F7 


CD3404 


01FA 


112E06 


01FD 


0E09 


01FF 


CD0500 


0202 


C31E01 



0205 


119F05 


0208 


CBF303 


020B 


3AB607 


020E 


47 


020F 


21B707 


0212 


EB 


0213 


C5 


0214 


211107 


0217 


3A1007 


021A 


B5 


021B 


C04E02 


021E 


B1 


021F 


215307 


0222 


3A5207 


0225 


A7 


0226 


D5 


0227 


C44E02 


022A 


El 


022B 


C0F003 


022E 


BA4502 


0231 


1E0A 


0233 


CD0A04 


0236 


3AD507 


0239 


5F 


023A 


1600 


023C 


19 


023B 


CI 


023E 


05 


023F 


C21202 


0242 


C31E01 


0245 


CI 


0246 


0E01 


0248 


CD0500 


024B 


C31E01 



BELAY 



TOUT 



PRTMX 



LXI 

BCX 

XTHL 

XTHL 

H0V 

0RA 

JNZ 

POP 

DCR 

JNZ 

HUI 

SUB 

STA 

INR 

BCR 

HUI 

CNZ 

LXI 

LBA 

HOU 

HUI 

LXI 

CALL 

LXI 

LBA 

HOU 

HUI 

LXI 

CALL 

LXI 

HUI 

CALL 

JMP 



[i,0 
D 



,-BELAY TO ALL0U RETURN OF CARRIAGE 



A,E 

B 

BELAY 

D 

C 

0UTLP 

A, 255 

C 

LINES 

C 

C 

C,1 

CPH 

H,HAXU 

HAX 

E,A 

D,0 

8,3*254+10 |USE DECIMAL 

BT0A 

H,MINU 

MIN 

E,A 

8,0 

8,3*256+10 

BT0A 

B.HAXHIN ;PRINT THIS DATA N0U 

C,9 

CPM 

UHAT 



;bone uith page? 

jc0hpute number of lines used 



JRETRIEVE CHARACTER TYPED 

;UNLESS THERE UAS NONE. 

JSETUF THE MAX AND MIN UALUES FOR THE 

JUSER TO SEE 



PRINT OUT THE IHAGE. THERE ARE TU0 TONE ARRAYS THAT UILL BE 
USEB FOR EACH LINE SUCH THAT 'OvERSTRIKE ' MAY BE USED UITH A 
PRINTER THAT B0ES NOT BACKSPACE. EACH TONE ARRAY UILL BE 
C0NSIBEREB SEPERATLY (THEY BON'T HAVE TO BE THE SAME LENGTH). 
THIS WILL ALLOU THE USER TO HAUE LOTS OF CONTROL OUER THE 
OUTPUT, IF HE/SHE CAN EUER BECIDE ON UHICH CHARACTERS TO USE. 



PRT 



PRTLP 



POUT 



LXI 

CALL 

LDA 

HOU 

LXI 

XCHG 

PUSH 

LXI 

LDA 

PUSH 

CALL 

POP 

LXI 

LDA 

ANA 

PUSH 

CNZ 

POP 

CALL 

JC 

HUI 

CALL 

LDA 

HOU 

HUI 

DAD 

POP 

DCR 

JNZ 

JHP 

POP 

HUI 

CALL 

JHP 



D.POS 

ASK 

LINES 

B,A 

H,BUFF 



H.T0NE1 

NUHBR1 

8 

PRINTLN 

8 

H.T0NE2 

NUHBR2 

A 

8 

PRINTLN 

H 

CHECK 

POUT 

E, 10 

PRINT 

LNGTH 

E,A 

8,0 

[i 



JTELL USER TO REABY PAPER 

;THIS IS HOU LONG THE SCAN IS 

THE SCAN BATA STARTS HERE. 

HOVE BATA AB8RESS TO (BE) 

SAUE LENGTH 

THIS IS THE PRIHARY TONE ARRAY 

ANB ITS LENGTH 

SAUE BATA ADDRESS 

PRINT THIS LINE 

RESTORE DATA ADDRESS 

HOU USE THE SECONDARY TONE ARRAY 

NOTE THAT THIS IS ZERO IF THERE IS 

NO SECONDARY ARRAY. 

SAUE ADDRESS 

;SET (HL) TO START OF LINE JUST PRINTED. 

;CHECK THE KEYBOARD 

;AND QUIT IF ANYTHING IS PRESENT 

;add A (LF> to the output FOR THE NEXT 

;line. 

jcompute start of next line 



;(hd has start address nou 
;decrehent line counter. 



PRTLP 

UHAT 

B 

C,1 

CPH 

UHAT 



;back TO option selection level 

;SET STACK STRAIGHT 
;GET CHARACTER TYPED 



;but ignore 



Listing 1 continued on page 228 



226 February 1981 © BYTE Publications Inc 



Computer experts 
(the pros) usually have big 
computer experience. 
That's why when they shop 
system software for Z80 
micros, they look for 
the big system features 
they're used to. And that's 
why they like Multi-User 
OASIS. You will too. 



DATA INTEGRITY: FILE & 
AUTOMATIC RECORD LOCKING 



The biggest challenge 
for any multi-user system 
is co-ordinating requests 
from several users 
to change the same record 
atthe same time. 

Without proper 
co-ordination, the 
confusion and problems 
of inaccurate or even 
destroyed data can be 
staggering. 

Our File and Automatic 
Record Locking features 
solve these problems. 

For example: normally 
all userscanviewa 
particular record atthe 
same time. But, if that 
record is being updated 
by one user, automatic 
record locking will deny all 
other users access to the 
record until the up-date is 
completed. So records 
are always accurate, 
up-to-date and integrity 
is assured. 

Pros demand file & 
automatic record locking. 
OASIS has it. 

SYSTEM SECURITY: 

LOGON, PASSWORD 

& USER ACCOUNTING 



Controlling who gets on 
your system and what they 
do once they're on it is the 
essence of system security. 



(THEN COMPARE.) 



Without this control, 
unauthorized users could 
access your programs and 
data and do what they like. 
A frightening prospect 
isn't it? 

And multi-users 
can multiply the problem. 

But with the Logon, 
Password and Privilege 



Level features of Multi-User 



OASIS, a system manager 
can specify for each user 
which programs and files 
may be accessed — 
and for what purpose. 

Security is further 
enhanced by User 
Accounting — a feature that 



lets you keep a history 
of which user has been 
logged on, when and 
for how long. 

Pros insist on these 
security features. 
OASIS has them. 



EFFICIENCY: 
RE-ENTRANT BASIC 



A multi-user system 
is often not even practical 
on computers limited 
to 64K memory. 

OASIS Re-entrant 
BASIC makes it practical. 

How? 

Because all users use a 
single run-time BASIC 
module, to execute their 
compiled programs, less 



memory is needed. Even 
if you have more than 64K, 
your pay-off is cost saving 
and more efficient use 
of all the memory you have 
available— because it 
services more users. 

Sound like a pro feature? 
It is. And OASIS has it. 



AND LOTS MORE. 



Multi-UserOASIS supports 
as many as 1 6 terminals 
and can run in as little as 
56K memory. Or, with 
bank switching, as much 
as 784K. 

Multi-Tasking lets each 
user run more than one 
job at the same time. 

And there's our BASIC- 
a compiler, interpreter and 
debugger all in one. 
An OASIS exclusive. 

Still more: Editor; Hard 
& Floppy Disk Support; 
Keyed (ISAM), Direct & 
Sequential Files; Mail-Box; 



Scheduler; Spooler; 
all from OASIS. 

Our documentation is 
recognized assome of the 
best, most extensive, in the 
industry. And, of course, 
there's plenty of 
application software. 

Put it all together and it's 
easy to see why the real 
pros like OASIS. Join them. 
Send your order today. 




OASIS IS AVAILABLE FOR 

SYSTEMS: Alios: Cornpucorp:Cromemco: 
Delta Producls: Digital Group: Digital 
Microsystems; Dynabyte; Godbout: IBC; 
Index; Inlersystems; North Star: Onyx: 
SD Systems; TRS 80 Mod II: Vector 
Graphic: Vorimex 

CONTROLLERS: Bell Controls: Cameo; 
Corvus; Konan; Micromation: Micropolis: 
Tarbell; Teletek: Thmkertoys: X Comp 



Write for complete. 






free Application Software Directory, 




PLEASE SEND ME: 






Price 






with 


Manual 


Product 


Manual 


Only 


OPERATING SYSTEM 






(Includes: 






EXEC Language; 






File Management, 






User Accounting; 






Device Drivers; 






Print Spooler; 






General Text 






Editor; etc.) 






SINGLE-USER 


$150 


SI 7.50 


MULTI-USER 


350 


17.50 


BASIC COMPILER/ 






INTERPRETER/DEBUGGER 


too 


1500 


RE-ENTRANT BASIC 






COMPILER/INTERPRETER/ 






DEBUGGER 


150 


15.00 


DEVELOPMENT PACKAGE 






(Macro Assembler; 






Linkage Editor; 






Debugger) 


150 


25.00 


TEXT EDITOR & 






SCRIPT PROCESSOR 


150 


15.00 


DIAGNOSTIC & 






CONVERSION UTILITIES 






(Memory Test; 






Assembly Language; 






Conveners; File 






Recovery; Disk Test: 






File Copy from 






other OS; etc.) 


100 


15 00 


COMMUNICATIONS 






PACKAGE 












File Send & Receive) 


100 


15.00 


PACKAGE PRICE 






(All Of Above) 






SINGLE-USER 


500 


60.00 


MULTI-USER 


350 


60.00 


FILE SORT 


100 


15.00 


' COBOL-ANSI '74 


750 


35.00 



Order OASIS from: 

Phase One Systems, Inc. 

7700 Edgewater Drive, Suite 830 

Oakland, CA 94621 

Telephone (415) 562-8085 
TWX 910-366-7139 

NAME 

STREET (NO BOX=) 

CITY 

STATE ZIP 



AMOUNTS 

(Attach system description; 

add S3 for shipping, 

California residents add sales tax) 

□ Check enclosed □ VISA 

□ UPS C.O.D. □ Mastercharge 

Card Number 

Expiration Date 

Signature 



MAKES MICROS RUN LIKE MINIS 



Circle 153 on Inquiry card. 



MORE FOR YOUR ^ 

RADIO SHACK 
TRS-80 MODEL I ! 

THE DATAHANDLER 

DATABASE MANAGEMENT 
SYSTEM IN MMSFORTH 

Now the power, speed and compactness of 
MMSFORTH drive a major applications pro- 
gram for many of YOUR home, school and 
business tasks! Imagine a sophisticated 
database management system with flexibili- 
ty to create, maintain and print mailing lists 
with multiple address lines, Canadian or the 
new 9-digit U.S. ZIP codes, and multiple 
phone numbers, plus the speed to load hun- 
dreds of records or sort them on several 
fields in 5 seconds! Manage inventories with 
selection by any character or combination. 
Balance checkbook records and do CONDI- 
TIONAL reporting of expenses or other cal- 
culations. File any records and recall 
selected ones with optional upper/lower 
case match, in standard or custom formats. 
Personnel, membership lists, bibliographies, 
catalogs of record, stamp and coin collec- 
tions—you name it! ALL INSTANTLY, with- 
out wasted bytes, and with cueing from 
screen so good that non-programmers quick- 
ly master Its use! With manual, sample data 
files and custom words for mail list and 
checkbook use. 

Technical: Handles data as compressed in- 
dexed sequential subfiles of up to 25K char- 
acters (9K in 32K RAM). Access 1-4 data 
diskettes. Modified Quicksort. Optionally 
precompiles for 5-second program load. Self- 
adjusts for many routine mods. Structured 
and modular MMSFORTH source code ideal 
for custom modifications. 

THE DATAHANDLER V1.1, a very soph- 
isticated database management system 
operable by non-programmers (requires Disk 
MMSFORTH, 1 drive & 32K RAM); with 
manuals $59.95* 




FORTH 



THE PROFESSIONAL FORTH 
FOR TRS-80 MODEL I 

(Over 1,000 systems in use) 

MMSFORTH Disk System V1.9 (requires 1 

disk drive & 16K RAM) )ust $79.95* 

MMSFORTH Cassette System V1.8 (requires 
Level II BASIC & 16K RAM) $59.95* 

AND MMS GIVES IT 
PROFESSIONAL SUPPORT 

Source code provided 

MMSFORTH Newsletter 

Many demo programs aboard 

MMSFORTH User Groups 

Programming staff can adapt 

THE DATAHANDLER to YOUR needs. 

MMSFORTH UTILITIES DISKETTE: includes 
FLOATING POINT MATH (L.2 BASIC ROM 
routines plus Complex numbers, 
Rectangular-Polar coordinate conversions, 
Degrees mode, more), plus a full Forth-style 
Z80 ASSEMBLER; plus a powerful CROSS- 
REFERENCER to list Forth words by block 
and line. All on one diskette (requires 
MMSFORTH, 1 drive & 16K RAM), . . $39.95' 

FORTH BOOKS AVAILABLE 

MICROFORTH PRIMER (comes with 

MMSFORTH) separately $15.00* 

USING FORTH — more detailed and advanc- 
ed than above $25.00* 

THREADED INTERPRETIVE LANGUAGES- 
advanced, excellent analysis of 

MMSFORTH-like language $18.95* 

CALTECH FORTH MANUAL — good on 

Forth internal structure, etc $10.00* 

* — Software prices include manuals and re- 
quire signing of a single-system user 
license. Add $2.00 S/H plus $1.00 per addi- 
tional book; Mass. orders add 5% tax. 
Foreign orders add 15%. UPS COD, VISA & 
M/C accepted; no unpaid purchase orders, 
please. 

Send SASE lor free MMSFORTH information. 
Good dealers sought 

Get MMSFORTH products from your 
computer dealer or 

MILLER MICROCOMPUTER 
SERVICES (B2) 

61 Lake Shore Road, Natick, MA 01760 
(617)653-6136 



Listing 1 continued 



024E 


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02S2 


47 


0253 


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025? 


0600 


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025D 


04 


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0262 


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0266 


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0268 


D5 


026? 


3AD507 


026C 


47 


026D 


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0270 


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0272 


3C 


0273 


F5 


0274 


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0277 


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1600 


027B 


?3 


027C 


DA8302 


027F 


14 


0280 


C37B02 


0283 


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0284 


3D 


0285 


BA 


0286 


DA8A02 


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7A 


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D5 


028C 


83 


028D 


5F 


028E 


3E00 


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8A 


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02?2 


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0293 


5F 


02?4 


CD0A04 


0297 


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0298 


05 


02?? 


C26D02 


029C 


1E0D 


029E 


CD0A04 


02AI 


D1 


02A2 


C? 



PRINT OUT ONE LINE OF IMAGE DATA. ONE ENTRY, (HL) POINTS TO 
THE TONE ARRAY TO USE AND (A) CONTAINS ITS LENGTH. THE SCAN 
DATA TO USE IS POINTED TO BY ( DE ) . ALL REGISTERS ARE USED BY 
THIS ROUTINE AND NOT RESTORED. 



PRINTLN 



DIVLP 



D1 



0UTLP1 



INLP1 



DIVLP1 



D2 



D3 



MOV 

LDA 

MOV 

LDA 

SUB 

MVI 

SUB 

JC 

INR 

JMP 

MOV 

STA 

ANA 

RZ 

XCHG 

PUSH 

LDA 

MOV 

LDA 

SUB 

CHA 

INR 

PUSH 

LDA 

MOV 

POP 

MVI 

SUB 

JC 

INR 

JMP 

MOV 

DCR 

CMP 

JC 

MOV 

POP 

PUSH 

ADD 

MOV 

MVI 

ADC 

MOV 

LDAX 

MOV 

CALL 

INK 

DCR 

JNZ 

MVI 

CALL 

POP 

RET 



C,A 

MIN 

B,A 

MAX 

B 

B,0 

C 

D1 

B 

DIVLP 

A,B 

SCALE 

A 



D 

LNGTH 

B,A 

MIN 

M 

A 

PSU 

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E,A 

PSU 

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E 

D2 

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D3 

A,D 

D 

D 

E 

E,A 

A,0 

D 

D,A 

D 

E,A 

PRINT 

H 

B 

INLP1 

E,I3 

PRINT 

D 



JSAVE LENGTH OF TONE ARRAY. 
•COMPUTE (MAX-MIN)/LENGTH 



-save result here 
-reject bad image data 

;(hl)=scan data, (de)=t0ne array 
"and save this on the stack 
;c0lumn limit 

jcompute: (data-mini/scale 
;nou <a>=min-data 

;nou (a>=dtat-nin 



•DON'T ALL0U IT TO BE TOO BIG 



; ITS 0K, JUST USE IT. 

•GET THE A(TH> BYTE FROM THE TONE STRING 



•GET THE BYTE TO PRINT 
;next BYTE 

;ADD (CR) 

JCLEANUP STACK 
; AND BACK OUT 



FILE THE DATA AUAY ON THE SUER SPECIFIED FILE. ON ENTRY TO 
IMAGE, THIS FILENAME UAS SPECIFIED (HOPEFULLY) AND UE HAVE 
ALREADY ADDED THE EXTENSION 'IMG' TO IT. IF THE INDICATED 
FILE ALREADY EXISTS, IT UILL BE DELETED AND A NEU FILE IS 
CREATED. THE INFORMATION SAVED UILL BE THE SCAN DATA ARRAY 
ITSELF, THE MAXIMUM AND MINIMUM VALUES IN THIS ARRAY, THE 
NUMBER OF SCAN LINES PRESENT, AND THE LENGTH OF EACH LINE. 
THIS DATA MAY BE READ BACK IN AT ANOTHER TIME UITH THE 'R' 
COMMAND. 



JCHECK FOR ANYTHING TO FILE 

Listing 1 continued on page 230 



02A3 


3A0807 


FILE 


LDA 


NSECT 


02A6 


A7 




ANA 


A 


02A7 


CA0403 




JZ 


NOTHING 



Are important letters and reports 
leaving your office with spelling errors? 




ELLGUARD 

can proofread 
10,000 words 
in one minute. 



SPELLGUARD is a revolutionary new computer program that finds 
spelling mistakes and typographical errors in documents prepared with 
CP/M 1 or CDOS 5 compatible word processors and text editors. 

In less than one minute, SPELLGUARD proofreads 20 pages of text 
(10,000 words) and identifies all misspelled or mis-typed words based on 
its 20,000-word dictionary* After proofreading, SPELLGUARD asks 
the operator to review words identified as potential errors and judge each 
as correct or incorrect. Correct words may be added to the dictionary. 
SPELLGUARD marks incorrect words in the text so the operator can use 
a word processor or text editor to easily find and correct them. 

SPELLGUARD is Easy to Use 

• full proofreading capabilities are mastered after a few minutes of 
instruction. 

• comprehensive user's manual contains step-by-step examples of all 
SPELLGUARD features. 

SPELLGUARD is Powerful 

• text files to 85 pages (CP/M 1.4), and 2,800 pages (CP/M 2.0). 

• includes a 20,000-word, expandable dictionary. 

• contains powerful commands to construct customized dictionaries for 
special areas, e.g., medicine, real estate, law, insurance, engineering. 

SPELLGUARD is Reliable 

• thoroughly tested in actual use. 

• 30-day money-back limited warranty. 

Minimum System Requirements: 8080/85, Z80 CPU with 32K memory: CP/M' 1.4 (dictionaries to 

256K bytes), CP/M' 2.0 or later (dictionaries to 4 MB), or CDOS; word processor or text editor 

compatible with SPELLGUARD (currently several excellent new CP/M word processors, and 

WordStar 2 , WordMaster 2 , Magic Wand 3 , Electric Pencil 4 , and ED). 

Trademarks: 'Digital Research (registered). 2 MicroPro Int'l Corp., ; 'Small Business Applications, 

"■Michael Shrayer Software, 5 Cromenco. 

*Time estimates based on 4Mhz 8085 with 48K memory, CP/M 2.1 double density 8" floppy drive, 

10,000-word text file. 



INNOVATIVE SOFTWARE APPLICATIONS 

Box 2797, Menlo Park, California 94025 415-326-0805 



The price of SPELLGUARD includes 
rapid turnaround and delivery by UPS or 
airmail. Sales will be made only if the 
purchasers' word processor is compatible 
with SPELLGUARD. Software license 
agreement is required. 

□ Send me a free, detailed description of 
SPELLGUARD. 

□ Send me SPELLGUARD at $295.00. 
(Manual and diskette(s). Formats: 8" 
CP/M single density Shugart compat- 
ible, and 5'/4" Northstar double.) 

□ Send me copies of the 

SPELLGUARD manual at $20.00 each. 
(Airmail, credited toward purchase.) 

□ Send COD (add $10.00 handling). 
California residents add 6% tax. 
Add $10.00 for foreign shipment. 

Check enclosed for$ . 

(Certified check, COD, and money order 
shipped immediately.) 



ORGANIZATION 



WORD PROCESSOR 



COMPUTER SYSTEM 



DISK FORMAT 



Checks payable to ISA 

Box 2797, Menlo Park, CA 94025. 




STATE-OF-THE-ART 
SOFTWARE 



Circle 154 on inquiry card. 



BYTE February 1981 229 



The joy of music — 

without years of practice! 




ALF offers the very finest in music 
hardware and software for the 
Apple® II. You can enter your own 
songs from sheet music and play 
them back very easily — our de- 
tailed manual shows you how, step 
by step. And there's a growing 
library of preprogrammed songs 
available too — now over 115 songs 
on 7 "albums", priced under $15 
each. ALF's highly acclaimed music 
software has many features found 
on no other Apple music product — 
and no customer has ever reported a 
"bug" or error. 

Whether you pick our exciting 
9-voice MCI music card at just 
$195, or our gourmet 3-voice MC16 
card at $245, you'll get ALF's top- 
quality hardware that's famous for 
reliability and clean sound (we've 
been designing computer-controlled 
musical instruments since 1975). 

So see your Apple dealer today, and 
be sure to specify ALF music cards 
for the best performance. When 
you've seen ALF's total music 
package, you'll know why some 
music cards are more equal than 
others! 

Please mention this magazine when 
requesting information from: 

<^|\ A L F Products Inc. 

^&? 1448 Estes Denver. CO 80215 (303) 234-0871 
Apple is a trademark of Apple Computer Inc. 



Listing 1 continued: 



DISK COPYING 

Dependable, no-hassle copying of 
Apple-compatible disks (all formats, 
including copy-protected). Fast 
service on 50 copies or thousands 
of copies. Mix titles for quantity 
discounts. Call or write for more 
information. 

ALF Products Inc. 

1448 Estes Denver, CO80215 
(303)234-0871 



02AA 
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02B2 
02B5 
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;create it n0u 
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;no rooh 

;this is uhere it is stored. 
;set initial sector counter to zero 
;in default fcb. 
;and this is hou long 

;set the transfer address 

jurite this sector 



;check status of last urite 
;hust be out of space 
;c0hpute address of next 



;CL0SE THE FILE NQU 



;TELL USER TO SCAN S0HETHING FIRST. 



READ IN THE FILE THAT UAS GIVEN IN THE INITIAL C0HHAND. 



READF 



READLP 



READDN 



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;SET THE TRANSFER ADDRESS 
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D.005CH ;READ A SECTOR 
C,20 
CPH 
A 
READDN 

D, 128 
H 
D 

PSU 
A 

READLP 
PSU 
NSECT 

D,005CH ;CL0SE THE FILE 

C,1 6 

CPH 

Listing 1 continued on page 232 



fZERO IS A GOOD READ 



;C0HPUTE NEXT ADDRESS 
;C0UNT THEH SECTORS READ. 



;SAVE SECTORS READ 



230 February 1981 © BY! E Publications Inc 



Circle 156 on inquiry card. 



Ten reasons 



l 



BASF FlexyDtok 1 
No. 



rr%!3 $r 



More than four decades of experi- 
ence in magnetic media -BASF 
invented magnetic recording 
tape, the forerunner of today's 
wide range of magnetic media, 
back in 1934, and was the first 
independent manufacturer of 
IBM-compatible floppy disks. 



Tough Tyvek sleeve — no paper 
dust, no static electricity. 



Special self -cleaning jacket and 
liner help eliminate data errors 
and media wear and tear. 



BASF BASF RexyDisk 



Center hole diameter punched to 
more accurate standards than 
industry specifications, for top 
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Packaging to suit your 
requirements - standard flip-top 
box, Kassette 10® storage case, 
or bulk pack. 



Bi-axially oriented polyester 
substrate - for uniform and reli- 
able performance year after year. 



Cross-linked oxide coating-for 
low head wear and long trouble- 
free media life. 



Total capability- one of two man- 
ufacturers in the world that 
iimakes both 8" and 5.25" models, 
has tape and disk experience, and 
manufactures floppy disk drives. 



Double lubrication -lubricants 
both in the formula and on the 
disk surface, to minimize media 
wear due to head friction. 



100% certification- every single 
disk is tested at thresholds 2-3 
times higher than system require- 
ments, to be 100% error-free. 



For the name of your nearest 
supplier, write BASF Systems, 
Crosby ■rive, Bedford, 
MA 01730, or call 617-271-4030. 
See us at the NCC, Booth 1121 




BASF 



Floppy Disks Mag Cards Cassettes Computer Tapes Disk Packs Computer Peripherals 



Circle 157 on Inquiry card. 



PERSONAL 

COMPUTER 

SYSTEMS 
topple computer 

■ Sales and Service 




APPLE II, 16K, List $1 195 $ 989 

32K, List $1395 $1169 

48K 1259 

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OUR PRICE ONLY $499 

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• Extended BASIC Language 

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• CRT Built-in Display 

• Magnetic Tape Cartridge for Storage 



CALCULATORS BY 



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PACKARD 



HP-41C Calculator, "A System" . . $244.95 
HP-32E Scientific w/Statistics ... $ 53.95 
HP-33C Scientific Programmable . . . 99.95 
HP-34C Advanced Scientific 

Programmable 123.95 

HP-37E Business Calculator 58.95 

HP-67 Handheld Fully Advanced 

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HP-97 Desktop w/Built-in Printer . . 579.95 



COMMODORE PET Call for Prices 

Prices do not include shipping by UPS. All 
prices and offers are subject to change without 
notice. 



R 



ersonal 
omputer 
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609 Butternut Street 

Syracuse, N.Y. 13208 

(315) 478-6800 

'232 February 1981 © BYTE Publications Inc 



Listing 1 continued: 



034C C3DC01 




JHP 


034F 117706 


I 

NOFILE 


LXI 


0352 0E09 




HVI 


0354 CD0500 




CALL 


0357 C31E01 




JHP 



039C 
039F 
03A0 
03A2 
03A5 
03A6 
03A7 
03A8 
03A9 
03AA 
03AB 
03AC 
03AE 
03B1 
0363 
03B6 
03B7 
03B8 
03B9 
03BA 
03BB 
03BC 
03BP 
03BE 
03BF 
03C0 



110907 

D5 

0E0A 

CD0500 

AF 

El 

23 

4E 

23 

47 

7E 

B630 

FAC403 

FE0A 

B2C403 

57 

78 

A7 

17 

5F 

17 

17 

83 

82 

0D 

C2A903 



PRTHX ;GIVE DENSITY LIHITS. 

D,NFHSG ;TELL USER THAT THIS FILE IS NOT 

C,9 ;SAVED. 

CPM 

UHAT ;BACK TO OPTION LEVEL 



SET THE TONE ARRAYS TO THE USER'S CHOICE. BOTH THE PRIMARY 
AND SECONDARY TONE ARRAYS HUST BE SET. EITHER ONE NAY BE BLANK. 



035A 11B405 TSET LXI 


D.MSG1 




035D 0E09 


HVI 


C,9 




035F CD0500 


CALL 


CPH 




0362 110F07 


LXI 


D,INPUT1 


;PUT THE STRING HERE 


0365 0E0A 


HVI 


C,10 


;USE CP/H'S LINE INPU 


0367 CD0500 


CALL 


CPH 




036A 110E06 


LXI 


D.HSG2 


;ASK FOR SECONDARY AR 


036D 0E09 


HVI 


C,9 




036F CD0500 


CALL 


CPH 




0372 115107 


LXI 


D,INPUT2 


;PUT IT HERE 


0375 0E0A 


HVI 


C , 1 




0377 CD0500 


CALL 


CPH 




037A C31E01 


JHP 


UHAT 


,N0THING TO IT, 



SECTION TO GET THE DESIRED HAXIHUH AND MINIMUM VALUES FR0H 
THE USER. THESE VALUES UILL REPLACE THOSE FOUND BY SCANNING 
THE DATA RECEIVED FR0H THE A/D. THIS UILL BE NECESSARY FOR 
THOSE CASES UHERE A PICTURE UAS BROKEN UP INTO H0RE THAN ONE 
IHAGE (DUE TO SIZE) AND A CONSISTENT SET OF CHARACTER 
SUBSTITUTIONS IS DESIRED. 



037D 119F06 SETHAX LXI 


D.SETHX 


JTELL USER UHICH ONE TO TYPE. 


0380 0E09 


HVI 


C,9 




0382 CD0500 


CALL 


CPH 




0385 CD9C03 


CALL 


GETNUH 


;and get it. 


0388 32D307 


STA 


HAX 


;and save it. 


038B 11D006 


LXI 


D.SETHN 


;N0U DO THE SAHE FOR THE HIN VALUE 


038E 0E09 


HVI 


C,9 




0390 CD0500 


CALL 


CPH 




0393 CD9C03 


CALL 


GETNUH 




0396 32D407 


STA 


HIN 




0399 C31E01 


JHP 


UHAT 


;N0 CHECK IS HADE FOR LEGAL VALUES 



ROUTINE TO READ IN A DECIHAL NUHBER TYPED BY THE USER. THE 
RESULTING VALUE IS RETURNED IN REGISTER (A). ALL REGISTERS ARE 
USED AND NOT RESTORED. 



GETNUH 



GETNH1 



LXI 


D,INBU 


PUSH 


B 


HVI 


C,10 


CALL 


CPH 


XRA 


A 


POP 


H 


INX 


H 


HOV 


C,H 


INX 


H 


HOV 


B,A 


HOV 


A,H 


SUI 


'0' 


JH 


BADNUH 


CPI 


10 


JNC 


BADNUH 


HOV 


D,A 


HOV 


A,B 


ANA 


A 


RAL 




HOV 


E,A 


RAL 




RAL 




ADD 


E 


ADD 


D 


DCR 


C 


JNZ 


GETNH1 



D.INBUFF JINPUT BUFFER TO USE 



;use cp/h's input routine to allow 
corrections. clear the accuhulator. 
jpoint to buffer 
;and skip over both counters 
;get count anb save in (c>. 

;save resulting value in (b) 
;get a character 
;hake binary 

;legal? 

jit's ok, save it here, 
jhultiply previous total by 10. 
jclear the carry flag. 



;ADD IN NEU DIGIT. 
;D0 ALL DIGITS. 

Listing 1 continued on page 234 



APPLE II ® TRS'80 <d 

QUALITY DISK SOFTWARE 

HOME FINANCE PAK I: Entire Series $49.95 ®£) ELECTRONICS SERIES: Entire Series $259.95 ®0 





CHECK REGISTER AND BUDGET: This comprehensive CHECKING 
ACCOUNT MANAGEMENT SYSTEM not only keeps complete 
records, it also gives you the analysis and control tools you need to 
actively manage your account. The system provides routines for 
BUDGETING INCOME AND EXPENSE, AUTOMATIC CHECK 
SEARCH, and BANK STATEMENT RECONCILING. CRT or printer 
reports are produced for ACTUAL EXPENSE vs BUDGET, CHECK 
SEARCH DISPLAY, RECONCILIATION REPORT and CHECK 
REGISTER DISPLAY by month. Check entry is prompted by 
user-defined menus of standard purposes and recipient codes, speeding 
data entry and reducing disk storage and retrieval time. Six fields of 
data are stored for each check: amount, check no., date, purpose, 
recipient and TAX OEOUCTIBLE REMINDER. CHECK SEARCH 
routines allow searching on any of these data fields. Routines are also 
provided for CHECK SORT by date and check no., DATA EDITING 
and Report Formats. Up to 100 checks/mo. storage $39.95 

SAVINGS: Account management system for up to 20 separate Savings 
accounts. Organizes, files and displays deposits, withdrawals and 
interest earned for each account. Complete records shown via CRT or 
printer $14.95 

CREDIT CARD: Get Control of your credit cards with this program. 
Organizes, stores and displays purchases, payments and service charges 
for up to 20 separate cards. Use for credit cards or bank loans. CRT or 
printer reports $14.95 

UNIVERSAL COMPUTING MACHINE: $49.95®® 

A user programmable computing system structured around a 5 row x 
50 column table. User defines row and column names and equations 
forming a unique computing machine. Table elements can be multiplied 
multiplied, divided, subtracted or added to any other element User can 
define repeated functions commonto row or column greatly simplifying 
table setup. Hundreds of unique computing machines can be defined, 
used and stored, and recalled, with or without old data, for later use. 
Excellent for sales forecasts, engineering design analysis, budgets, inven- 
tory lists, income statements, production planning, project cost 
estimates in short for any planning, analysis or reporting problem that 
can by solved with a table. Unique curser commands allow you to move 
to any element, change its value and immediately see the effect on 
other table values. Entire table can be printed by machine pages 
(user-defined 3-5 columns) on a 40 column printer. 

COLOR CALENDAR: $29.95® 

Got a busy calendar? Organize it with Color Calendar. Whether it's 
birthdays, appointments, business meetings or a regular office schedule, 
this program is the perfect way to schedule your activities. 
The calendar display is a beautiful HI-RES color graphics calendar of 
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Using the daily schedule, you can review any day of the month and 
schedule an event or activity in any one of 20 time slots from 8:00 
A.M. to 5:30 P.M. Your description can be up to 20 characters long. 
The system will also print out hard copies on your minimum 40-column 
printer. 

BUSINESS SOFTWARE: Entire Series $159.95 ®(D 

MICROACCOUNTANT: The ideal accounting system for small busi- 
nesses. Based on classic T-accounts and double-entry booking, this 
efficent program provides a ledger journal for recording, posting and 
reviewing up to 1,000 transactions per month to any one of 300 
accounts. The program produces CRT and printer reports covering: 
Transaction Journal Balance Sheet 
Account Ledgers Income and Expense Statement 
Includes a short primer on Financial Accounting. Requires 48K Ram 
$49.95 

UNIVERSAL BUSINESS MACHINE: This program is designed to 

SIMPLIFY and SAVE TIME fai the serious businessman who must 

periodically Analyze, Plan and Estimate. The program was created using 

our Universal Computing Machine and it is programmed to provide the 

following planning and forecasting tools. 

CASH FLOW ANALYSIS SALES FORECASTER 

PROFORMA PROFIT& LOSS SOURCE AND USE OF FUNDS 

PROFORMA BALANCE SHEET JOB COST ESTIMATOR 

REAL ESTATE INVESTMENT INVENTORY ANALYSIS 

Price, including a copy of the Universal Computing Machine . . .$89.95 

BUSINESS CHECK REGISTER AND BUDGET: Our Check Register 
and Budget programs expanded to include up to 50 budgetable items 
and up to 400 checks per month. Includes bank statement reconciling 
and automatic check search (48K) $49.95 



LOGIC SIMULATOR: SAVE TIME AND MONEY. Simulate your 
digital logic circuits before you build them. CMOS, TTL, or whatever, if 
it's digital logic, this program can handle it. The program is an 
interactive, menu driven, full-fledged logic simulator capable of 
simulating the bit-time response of a logic network to user-specified 
input patterns. It will handle up to 1000 gates, including NANOS, 
NORS, INVERTERS, FLIP-FLOPS, SHIFT REGISTERS, COUNTERS 
and user-defined MACROS. Up to 40 user-defined random, or binary 
input patterns. Simulation results displayed on CRT or printer. Accepts 
network descriptions from keyboard or from LOGIC DESIGNER for 
simulation $159.95 

LOGIC DESIGNER: Interactive HI-RES Graphics program for 
designing digital logic systems. A menu driven series of keyboard 
commands allows you to draw directly on the screen up to 1 5 different 
gate types, including 10 gate shape patterns supplied with the program 
and 5 reserved for user specification. Standard patterns supplied are 
NAND, NOR, INVERTER, EX-OR, T-FLOP, JK-FLOP, D-FLOP, 
RS-FLOP, 4 BIT COUNTER and N BIT SHIFT REGISTER. User 
interconnects gates just as you would normally draw using line graphics 
commands. Network descriptions for LOGIC SIMULATOR generated 
simultaneously with the CRT diagram being drawn $159,95 

MANUAL AND DEMO DISK: Instruction Manual and demo disk 
illustrating capabilities of both programs $29.95 

MATHEMATICS SERIES: Entire Series $49.95 ® 

STATISTICAL ANALYSIS I: This menu driven program performs 
LINEAR REGRESSION analysis, determines the mean, standard 
deviation and plots the frequency distribution of user-supplied data 
sets. Printer, Disk, I/O routines $19.95 

NUMERICAL ANALYSIS: HI-RES 2-Dimensional plot of any 
function. Automatic scaling. At your option, the program will plot the 
function, plot the INTEGRAL, plot the DERIVATIVE, determine the 
ROOTS, MAXIMA, MINIMA, INTEGRAL VALUE $19.95 

MATRIX: A general purpose, menu driven program for determining the 
INVERSE and DETERMINANT of any matrix, as well as the 
SOLUTION to any set of SIMULTANEOUS LINEAR EQUATIONS. 
$19.95 

3-D SURFACE PLOTTER: Explore the ELEGANCE and BEAUTY of 
MATHEMATICS by creating HI-RES PLOTS of 3-dimensional surfaces 
from any 3-variable equation. Disk save and recall routines for plots. 
Menu driven to vary surface parameters. Hidden line or transparent 
plotting $19.95 

ACTION ADVENTURE GAMES: Entire Series $29.95 ® 

RED BARON: Can you outfly the RED BARON? This fast action game 
simulates a machine-gun DOGFIGHT between your WORLD WAR I BI- 
PLANE and the baron's. You can LOOP, DIVE, BANK or CLIMB-and 
so can the BARON. In HI-RES graphics $14,95 

BATTLE OF MIDWAY: You are in command of the U.S.S. HORNETS' 
DIVE-BOMBER squadron. Your targets are the Aircraft carriers, Akagi, 
Soryu and Kaga. You must fly your way through ZEROS and AA FIRE 
to make your DIVE-BOMB run, In HI-RES graphics $14.95 

SUB ATTACK: It.s April 1943. The enemy convoy is headed for the 
CORAL SEA. Your sub, the MORAY, has just sighted the CARRIERS 
and BATTLESHIPS' Easy pickings.But watch out for the 
DESTROYERS -they're fast and deadly. In HI-RES graphics $14.95 

FREE CATALOG-AM programs are supplied on disk and run on Apple 
II w/Disk 8t Applesoft ROM Card & TRS-80 Level II and require 32K 
RAM unless otherwise noted. Detailed instructions included. Orders 
shipped within 5 days. Card users include card number. Add $1.50 
postage and handling with each order. California residents add 6'/:% 
sales tax. Foreign orders add $5.00 postage and handling. 

142 Carlow 
SPECTRUM P-O.Box 2084 
SOFTWARE Sunnyvale, CA 94087 

FOR PHONE ORDERS:(408)7384387 

DEALER INQUIRIES INVITED. 




Circle 158 on inquiry card. 



BYTE February 1981 233 



Circle 159 on inquiry card. 




CTC-101 Terminals 

we're overstocked on these 
powerful, reliable standard 
data terminals. The GT-101 is 
Z-80 based with standard 
printer port, user-settable 
clock, 8 user-programmable 
function keys and much 
more! Order Today! Limited 
Quantities. 

Reg. S999.00 S7QC 

Clearance Price Only / <j D 




CTA ADC-16C 

16 Channel variable 

a-d Board! 

can be used for 
Position /Pressure /Photo- 
electric/and Temperature 
Measurements, and as a 
computerized Volt/Ohm 
meter. Board is shipped with 
operating manual, software, 
and a test conducter. For use 
with Apple ll/lll. ._--,. 

Introductory Price I /<j 

NOTE: Soon To Be Available - 
CTA's new 16K Memory Board! 



CTA I 



COMPUTER 

TECHNOLOGY 

ASSOCIATES 



5812 cromo Drive, Suite 102 

El Paso, Texas 79912 

(915) 581-3500 

Visa/MasterCard/Diner's Club Accepted. 

TO ORDER: Send check, money order or 
credit card number and exp. date to 
Computer Technology Associates, 5812 
Cromo Drive, Suite 102. El Paso, Texas 
79912. Personal or company checks 
require two weeks to clear, credit card 
users can call with card information. 

shipping: we ship terminals prepaid by 
motor freight. Air and express delivery 
are available on all products. 

There is no handling charge. 



Listing 1 continued: 
03C3 C9 



03C4 11DD06 

03C7 0E09 

03C9 CD0500 

03CC C39C03 



03F3 0E09 
03F5 CD0500 
03F8 0E01 
03FA C30500 



RET |ALL DONE, RESULT IS IN (A). 

BADNUM LXI D.BADINP ;TELL USER TO TRY AGAIN. 

HVI C,9 

CALL CPH 

JHF GETNUH 



READ THE A/D AND AVERAGE OVER EIGHT READS TO REDUCE THE 
SCATTER THAT IS BOUND TO EXIST UITH THIS SIMPLE IMAGE 
PROCESSING SYSTEM. 



03CF 


E5 


READ 


PUSH 


H 




03D0 


C5 




PUSH 


B 




03D1 


210000 




LXI 


H,0 


;KEEP SUM HERE 


03D4 


0608 




HVI 


B,8 




03D6 


CD1604 


RLP1 


CALL 


AT0D 


|READ THE A/D 


03D9 


85 




ADD 


L 


;add VALUE TO OUR sum 


03DA 


6F 




NOV 


L,A 




03DE 


3E00 




HVI 


A,0 




03DD 


BC 




ADC 


H 




03DE 


67 




MOV 


H,A 




03DF 


05 




DCR 


B 




03E0 


C2D603 




JNZ 


RLPt 




03E3 


0603 




MVI 


B,3 


;nou divide by s 


03E5 


A7 


RLP2 


ANA 


A 


;CLEAR CARRY 


03E6 


7C 




MOV ■ 


A,H 




03E7 


1F 




RAR 






03E8 


67 




MOV 


H,A 




03E9 


7D 




MOV 


A,L 




03EA 


IF 




RAR 






03EB 


6F 




MOV 


L,A 




03EC 


05 




DCR 


B 




D3ED 


C2E503 




JNZ 


RLP2 




03F0 


C1 




POP 


B 




03F1 


El 




POP 


H 




03F2 


C9 


; 


RET 
JTILITY 


ROUTINES.. 





ASK A MESSAGE POINTED TO BY (DE), AND GET A ONE CHARACTER 
RESPONCE. THE RESP0NCE IS RETURNED IN (A). ALL REGISTERS 
ARE USED AND NOT RESTORED. 



ASK 



MVI C,9 

CALL CPM 

MVI C,1 

JMP CPM 



JPRINT MESSAGE AND GET RESPONCE 



CHECK THE KEYBOARD TO SEE IF ANYTHING IS READY. ON SYSTEMS 
THAT LATCH THE OUTPUT FROM THE TERMINAL, THE USER JUST HITS 
A KEY AND THEN THIS UILL DETECT IT. ON OTHER TYPES (LIKE MINE), 
THE USER MUST HOLD THE KEY DOUN UNTIL THIS ROUTINE IS CALLED. 
A MINOR INCONVENIENCE. ALL REGISTERS EXCEPT (A) ARE SAVED. 
IF A KEY IS TYPED, THEN THIS UILL RETURN UITH THE CARRY FLAG 
SET. 



;CHECK THE KEYBOARD FOR ANYTHING 



03FD C5 CHECK PUSH 


B 


03FE E5 


PUSH 


H 


03FF D5 


PUSH 


D 


0400 OEOB 


MVI 


C, 11 


0402 CD0500 


CALL 


CPM 


0405 Dl 


POP 


D 


0406 El 


POP 


H 


0407 CI 


POP 


B 


0408 IF 


RAR 




0409 C9 


RET 





SEND ONE CHARACTER TO THE LIST DEVICE. THE CHARACTER MUST BE 
IN REGISTER (E) AND ALL REGISERS (EXCEPT A) ARE SAVED. 



Listing 1 continued on page 236 



040A C5 


PRINT 


PUSH 


B 


JPRINT (E) 


040B E5 




PUSH 


H 




040C D5 




PUSH 


D 




040D 0E05 




MVI 


C,5 




040F CD0500 




CALL 


CPM 





234 February 1981 © BYTE Publications Inc 



"WITH THE UCSD p-SYSTEM,™ 
WE CAN WRITE ONE APPLICATION 
THAT GOES FROM APPLE TO ZENITH? 



HARRY BLAKESLEE, President, Denver Software 




UCSD p-System and UCSD Pascal are trademarks of the Regents of the University of California. 



Our business is bigger and 
better than ever. 
A lot of the credit for that 
goes to the UCSD p- System software 
from SofTech Microsystems. It's 
given us ten times the market we 
used to have. 

We can write a single, 
sophisticated applications program 
with the UCSD p-System — like our 
financial management package— and 
it just keeps on running. On Apple, 
Commodore, Ohio Scientific, Texas 
Instruments, Zenith, and more. 
That's the real beauty of the UCSD 
p-System. Any program you write for 
one microcomputer runs on others, 
both today and tomorrow. You protect 
your software investment, without 
restricting your hardware options. 

And with the UCSD 
p-System,you can use the language 
of your choice — UCSD Pascal,™ 
FORTRAN-77, BASIC, or assembly 
language. All are backed by SofTech 
Microsystems, a leading system 
software company who's been around 
for over a decade, who knows how 
to develop professional quality 
software, and who's committed to 
delivering it. 

Get a head start on tomor- 
row. With the microcomputer 
software that goes from "A" to "Z." 
Distribution licensing and single 
copies available. Write or call for 
details, so you can start going 
places, too. 

micRosvsTems 

Ft SUBSOWIV OF SOFTECH 

For the software that's going places. 

9494 Black Mountain Road, San Diego, 

CA 92126. (714) 578-6105 

TWX: 910-335-1594 



Circle 160 on inquiry card. 



BYTE February 1981 



235 



Circle 161 on inquiry card. 



Buy By Mail 
and Save! 




INTERTECSuperBank, 32K .$2495 

64K Ram, List $3345 $2695 

64K Quad, List $3995 $3395 

NORTH STAR Horizon I 

32K DD List $2695 $1989 

Horizon I QD List $2995 $2245 

Horizon 2 32K DD.List $3095 $2289 

lntersystemDP-1 List $1749 . .$1495 




t 



CROMENCO Z-2, List $9995 .$7945 

System 64K, List $3990 $3179 

System 3 64K, List $7395 5689 

ATARI 800, List $1080 $799 

APPLE II, 16K $969 

DISK SYSTEMS 

THINKER TOYS" Discus 2D ..$939 

Dual Discus 2D $1559 

Discus 2 + 2, List $1549 $1259 

M26 Hard Disk, List $4995 . . .$3949 

PRINTERS & TERMINALS 

PAPER TIGERS IDS-440 $679 

With graphic option $749 

CENTRONICS 730-1, List $795 $595 

737, List $995 $789 

704-9 180 cps $1495 

703-9 180 cps $1569 

T I 810,List S1895 $1489 

NECSPINWRITER5530 $2395 

NEC SPINWRITER 5515 $2395 

DIABLO 630 List $2711 $2399 

INTERTEC 

Intertube III.List $895 729 

Emulator $729 

Televldeo 912C $679 

920C $799 

Hazeltine1420 $789 

1500 $845 

Soroc 120, List $995 $689 

Soroc140 $994 

Most items in stock for immediate delivery. Factory sealed cartons, 
w/toll factory warranty. NYS residents add appropriate sales tax. 
Prices do not include shipping. VISA and Master Charge add 3%. 
C.O.D. orders require 25% deposit. Prices subject to change without 
notice. 

Computers 
Wholesale 

P.O. Box 144 Camillus, NY 13031 
S. (315)472-2582 



Listing 1 


conti 


tued: 






0412 D1 






POP 


D 


0413 El 






POP 


H 


0414 C1 






POP 


B 


0415 C9 






RET 





READ THE A/D. IT IS ASSUHED HERE THAT THE SETUP IS SIMILAR 
TO THAT PROPOSED IN DDJ, OCTOBER 1979. HERE, THE H/A IS 
CONNECTED TO OUTPUT PORT 2, AND THE RESULT OF THE COMPARITOR 
IS READ FROH INPUT PORT 2, BIT 0. FOR THE DIGITAL GROUP SYSTEN, 
THE INPUT DATA UILL BE INVERTED BY THE CPU CARD. IF YOURS DOES 
NOT UCRK THIS UAY, CHANGE THE 'JNZ' TO A 'JZ' IN THE CODE BELOU. 
THE RESULTING VALUE IS RETURNED IN IA) AND ALL OTHER REGISTERS 
ARE SAVED. THIS PROCEDURE USES A BINARY SEARCH TECHNIQUE TO FIND 
THE VALUE OF THE VOLTAGE INPUT TO THE A/D. 



0416 


C5 


ATOD 


PUSH 


B 


;READ A/D (.34 MS PER READ AVERAGE) 


0417 


AF 




XRA 


A 


;READ THE A/D 


0418 


0680 




HVI 


6,128 




041A 


0E08 




HVI 


C,8 




041C 


80 


ADLOOP 


ADD 


B 


;SET THE D/A 


041D 


D302 




OUT 


2 




041F 


F5 




PUSH 


PSU 




0420 


DB02 




IN 


2 


;READ AND CHECK BIT DO 


0422 


E601 




ANI 


1 




0424 


C22A04 




JNZ 


ADI 


;*** SYSTEM DEPENDENT **» 


0427 


F1 




POP 


PSU 




0428 


90 




SUB 


B 


;T00 FAR, BACK OFF 


0429 


F5 




PUSH 


PSU 




042A 


78 


ADI 


MOV 


A,B 


;next BIT 


042B 


1F 




RAR 






042C 


47 




MOV 


B,A 




042D 


Fl 




POP 


PSU 




042E 


OD 




DCR 


C 


;D0 ALL 8 BITS 


042F 


C21C04 




JNZ 


ADLOOP 




0432 


CI 




POP. 


B 




0433 


C9 




RET 







BINARY TO ASCII ROUTINE 

THIS ROUTINE UILL CONVERT A 16 BIT BINARY NUMBER INTO ASCII 
ACCORDING TO A SPECIFIED RADIX VALUE. THE DIGITS USED ARE: 
0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F,G,H,I,J,K ETC 

TO USE: 

HL=ADDRESS OF A BUFFER FOR THE RESULTING ASCII DIGITS 

DE=CONTAINS THE 16 BIT NUMBER TO CONVERT 

B =THE NAXIMUM LENGTH OF THE BUFFER 

C =THE RADIX TO USE (2,8, 16, .. .ETC) 

ON RETURN, THE CARRY FLAG IS SET IF AN OVER-FLOU OCCURED 
(BUFFER UAS TOO SHALL). 



0434 


3E30 


BTOA 


HVI 


A,'0' 


JADJUST THE RADIX FOR ASCII CONVERSION 


0436 


81 




ADD 


C 




0437 


FE3B 




CPI 


'9' + 2 




0439 


DA3E04 




JC 


BT0A1 




043C 


C607 




ADI 


7 




043E 


4F 


BT0A1 


MOV 


C,A 








; BLANK 


OUT THE BUFFER 


SPACE 


043F 


78 




MOV 


A,B 




0440 


3620 


BT0A2 


MVI 


■V ' 




0442 


23 




INX 


H 




0443 


3D 




DCR 


A 




0444 


C24004 




JNZ 


BT0A2 




0447 


2B 




DCX 


H 








; CONVERT THE 


NUMBER NOU. 


0448 


3630 




MVI 


N,'0' 


|ZER0 OUT THE FIRST DIGIT. 


044A 


7A 




MOV 


A,D 


JCHECK FOR ZERO 


044B 


B3 




ORA 


E 




044C 


C8 




RZ 






044D 


34 




INR 


M 


Listing 1 continued on page 




KIM 
AIM 



ANALOG INTERFACES 

Industrial, Scientific, Laboratory, 
or Commercial Microcomputer Users- 
industrial quality data conversion boards are available for 
APPLE, S-100, PET, TRS-80, AIM, and KIM systems. 
Tecmar can provide individual boards, data conversion 
subsystems, or complete Data Conversion Systems. 
Tecmar's growing productline offers outstanding features, 
meticulous engineering, exceptional documentation, and 
a seven year record of proven reliability. 



TRS-80 



Tecmar's new Analog to Digital Converter Series (AD-200) 
is designed to meet sophisticated data acquisition needs. The 
board accommodates various precision A/D modules made 
by Analogic and Data Translation. These modules are easily 
interchanged to provide options such as 12, 14, or 16 bit 
accuracy; 125 KHz throughput; variable ranges and gains. 
AD212 S-100 A/D and Timer Board $695 

AD211 Apple A/D Board $495 

AD-200 Features 

• 12 bit accuracy and resolution standard 

• 30 KHz conversion rate standard 

• 16 single-ended or 8 true differential inputs • jumper selectable 

• External trigger of A/D 

• Output formats: Two's complement, binary, offset binary 

• Auto channel incrementing from any channel to any channel 

• Data is latched providing pipelining for higher throughputs 

• Provision for synchronizing A/Ds 

• Utilizes interrupt or status test 

• Jumper selectable input ranges: ±10V, ±5V, Oto+lOV, Oto +5V 
In addition the S-l 00 version: 

• Complies with IEEE S-100 specifications 

• Transfers data in 8 or 16 bit words 

• Provides for expansion to 256 channels 

• Is switch selectable I/O or memory mapped 

Timer Features on S-100 Board 

In addition to the A/D features, the S-100 Board contains a 
powerful timer circuit which can start A/D conversion and can 
also be used independently for time of day, event counting, 
frequency shift keying and many other applications. 



• 5 independent 16 bit counters 
(cascadable) 

• 1 5 lines available for external use 

• Time of day 

• Event counter 

• Alarm comparators on 2 counters 

• One shot or continuous frequency 



• Complex duty cycle and frequency 
shift keying outputs 

• Programmable gating and count 
source selection 

• Utilizes vectored interrupt 



outputs 



Options for AD-200 



Programmable gain up to 500 

14 bit accuracy 

1 6 bit accuracy 

100 KHz conversion rate 

125 KHz conversion rate 

Screw Terminal and Signal Conditioning panel 

• Thermocouple cold junction compensation 

• Rack mounting assembly with plexiglass cover 
Low level, wide range permitting low level sensors 
such as thermocouples, pressure sensors and strain 
gauges to be directly connected to the module input 



$ 



175 
717 
1,117 
517 
617 
250 
125 
125 
70 



TRS-80 



Apple D/A Features $295 




12 bit accuracy and resolution 

2 independent digital to analog converters 

8 parallel latched output lines 

Jumper selectable output ranges: ±10V, ±5V, ±2.5V, 

Oto+lOV, Oto +5V 

• 3 microsecond conversion time 

• Minimal software required 

• Optional 4-20 mA board available 

S-100 PET 2 TRS-80 1 

The original Tecmar data conversion boards (AD-100 and 
DAT 00) continue to solve less sophisticated conversion 
problems. These S-l 00 boards interface to the PET, TRS-80, 
AIM, and KIM through S-100 expansion interfaces. 

AD- 1 00 Features $495 



AIM 3 KIM 2 



12 bit accuracy and 

resolution 

30 KHz conversion rate 

16 single-ended or 8 true 

differential inputs (specify 

AD-100SorAD-100D) 

Minimal software required 



I/O or memory mapped 
operation for S-100 
systems - jumper selectable 
Jumper selectable input 
ranges: +10V.+5V, 
Oto +10V, 0to+5V 
IEEE S-100 



DA- 100 Features $395 



• 12 bit accuracy 
and resolution 

• 4 independent digital to 
analog converters 

• 3 microsecond settling time 

• Jumper selectable output 
ranges: +10V, ±5V, +2.5V, 



Oto +10V,0to+5V 

• I/O or memory mapped 
operation for S-100 
systems - jumper selectable 

• Minimal software required 

• IEEE S-100 

• Optional 4-20 mA board available 
Expansion board, power supply, and enclosure for PET * 250 
Expansion board and power supply for TRS-80, KIM, or AIM 1 50 



S-100 Real Time 
Video Digitizer 

Digitizes and Displays in 
1/60 sec, flicker-free 
16 Gray Levels 
Switch Selectable to 
display Black and White 
Graphics (8 pixels/byte) 
Maximum Resolution: 
512 pixels/line x 240 lines 
Minimal software 
requirements $850 



EC 



RR 



INC. 



Data Acquisition Systems and 
Video Digitization Systems Available 

23414 Greenlawn • Cleveland, OH 44122 



S-l 00 BOARDS 

8086 CPU $450 

W/vectored interrupts 

RAM $395 

8Kxl6/16Kx8 

8086 $495 

PROM-I/O 

Serial and $350 

Parallel I/O 

Parallel I/O $350 

& Timer 

'Reg. Tiademarto of Tandy Corp. 
2 Reg. Tiademaik of Commodore 
J Reg. Tiademaito of Rockwell 



TECMAR, INC. 

(216)382-7599 



Circle 162 on inquiry card. 



Circle 163 on Inquiry card. 



Are your users 
saying . . . 

"@#* It should be 
here, but where?!" 

How much valuable 
time is wasted 
searching for items 
which should have 
been indexed? 

At Last, 
Indexing for 
WordStar™ 

DocuMate™ from 
the Orthocode 
Corporation solves 
this annoying problem. 

DocuMate™ features 

■ Table of Contents 
Generation 

■ Multi-level Indexing 

■ See and See also 
references 

DocuMate can make a table 
of contents automatically from any 
Wordstar text file. In conjunction 
with a sort utility such as 
Supersort™ it can also generate 
alphabetized, multi-level sorted 
indexes. 

Just put simple DocuMate 
commands in your text file; 
DocuMate does the rest. DocuMate 
commands look like comments to 
WordStar; they have no effect on 
your printed output. 

If you publish computer manuals or 
other documentation, nothing will 
give them that professional look 
like a good index. 

DocuMate is available now on 
standard 8" CP/M™ diskettes. 

■ Manual only - $5. 

■ CP/M version - $50. 

Add $4 for shipping & handling 

>5fflH®C0DE 

The Textware Company 

THE ORTHOCODE CORPORATION 

P.O. Box 6191 

Albany, California 94706 

Phone (415) 527-9300 

TWX 910 366-7046 

WORDSTAR & SUPERSORT ARE TRADEMARKS OF 

MICROPRO INTERNATIONAL 

CP'M IS A TRADEMARK OF DIGITAL RESEARCH. 



238 February 1981 © BYTE Publications Inc 



I 



Listing 1 continued: 

044E IB BLP OCX 

044F 7B HOv 

0450 B2 ORA 

0451 CB RZ 



B 

A,E 

B 



;roll boun counter 
|is it zero yet ? 



;yes then ue are bone, 
roll up the result in odometer fashion 



0452 E5 

0453 C5 

0454 7E 

0455 3C 

0456 B9 

0457 C26C04 
045A 3630 
045C 2B 
045D 05 
045E CA7504 

0461 7E 

0462 FE20 
0464 C25404 
0467 3630 
046? C35404 
046C 77 
046D FE3A 
046F C27504 
0472 C607 
0474 77 



0475 CI 

0476 E1 

0477 C24E04 
047A. 37 
047B C9 



BT0A3 



BT0A4 



PUSH 

PUSH 

MOV 

INR 

CHP 

JNZ 

MVI 

BCX 

DCR 

JZ 

HOV 

CPI 

JNZ 

NVI 

JHP 

MOV 

CPI 

JNZ 

ABI 

MOV 



H 

B 

A,M 

A 

C 

BT0A4 

M, 0' 

H 

B 

BT0A5 

A,M 

JT0A3 
H, '0' 
BT0A3 
M,A 
"9' + 1 
BT0A5 

M,A 



JKEEP REGS 



JREACHEI RABIX LIMIT ? 

JYES, RESET THIS BIGIT TO ZERO ANB U0RK 
JON THE NEXT (IF THERE IS ONE). 

JOVER-FLOU 

;CHANGE A BLANK INTO A ZERO FIRST TIME HERE 



jCHECK FOR A BIGIT >? ANB BUMP PAST SOME 
JASCII JUNK 



RESTORE THE REGS AND CONTINUE UNLESS THE ZERO FLAG IS SET. 



BT0AS 



POP 
POP 
JNZ 
STC 
RET 



B 
H 
BLP 



|SET THE CARRY ON AN 0VER-FL0U ERROR 



MESSAGE AREA 



047C 
049E 
04 B 5 
04BF 
04B0 
04E7 
050B 
0528 
0543 
0557 
056A 
0560 
0561 
059F 
05B8 
05D4 
05FC 
060E 
061B 
062E 
064A 
065A 
065F 
0677 
069F 
06C3 
06D0 
06DD 
0702 



0D0A494D41HELL0 

2020207665 

0D0A4B656E0PTI0N 

463B46696C 

483D48656C 

4B3B536574 

503B507269 

513B517569 

523D526561 

533B536361 

543B536574 

24 

0B0A4F7074QUESTN 

0B0A506F73P0S 

0B0A446973ERR1 

0B0A456E74MSG1 

3C7265743E 

0B0A536563MSG2 

0D0A4C696ELLNGTH 

0D0A496B61MAXMIN 

3030302C20MAXV 

3030302E24MINV 

0D0A4E6F20N0NE 

0B0A4E6F20NFMSG 

0B0A536574SETMX 

0B0A4B6178 

0B0A4B696ESETMN 

0B0A4F6E6CBABINP 

0B0A3F2024 



BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 
BB 



10, '"IMAGE Inage Processing Progran' 
ver 2.00 11-05-79*' 
10,'Henue:',13,10 
File the data', 13, 10 
Help, display nenue ■ ,13,10 
Set the naxinun and hininim values' , 13 ,10 
Print the data back out', 13, 10 
Quit and return to CP/M', 13, 10 
Read the file in', 13, 10 
Scan a new page', 13, 10 
Set the tone array', 13, 10 



10,' 

10,' 

10,' 

10,' 

et>' 

10,' 

10,' 

10,' 

0, n 

0.*' 

10, 

10,' 

10,' 

10,' 

10,' 

10,' 

10,' 



Option (F,H,M,P,Q,R,S,T) ? $' 

Position paper (space)*' 

Disk or directory is full*' 

Enter density characters (nax to Kin)," 

,13,10,'Prihary -?*' 

Secondary -?*' 

Line length -?*' 

Inage scanned: Max value =' 

in value =' 

No inage was scanned.*' 

No scan data was saved for this file.*' 

Setting naxinuK and nininun values' 

Ma Kin uh ? *' 

Minimin 1 *' 

Only digits 0-9 are allowed, retry." 

? *' 



BATA STORAGE AREA 



0707 00 SCALE BB 

0708 00 NSECT BB 

0709 0400000000INBUFF BB 
070F 40 INPUT1 BB 

0710 1E NUNBR1 DB 





JSECTORS USED IN SCAN 

4,0,0,0,0,0 JNUMERIC INPUT BUFFER 

64 JMAX LENGTH OF FRIMARY TONE ARRAY 

30 JCURRENT LENGTH 

Listing 1 continued on page 240 




Aflft ^B ^P Licenced I>t Sinclair Research Lid 

Microcomputer 

for everyone at 
a Micro Price 



The LMicrofkel 



The unique 

and valuable 

components of the MicroAce 

The MicroAce is not just another personal 
computer. Quite apart from its exceptionally low 
price, the MicroAce has two uniquely advanced 
components: the powerful BASIC interpreter, and 
the simple teach yourself BASIC manual. 

The unique versatile BASIC interpreter offers 
remarkable programming advantages: 

• Unique 'one-touch' key word entry: the 
MicroAce eliminates a great deal of 
tiresome typing. Key words (RUN, PRINT, 
LIST, etc.) have their own single-key entry. 

• Unique syntax check. Only lines with correct 
syntax are accepted into programs. A cursor 
identifies errors immediately. This prevents 
entry of long and complicated programs with 
faults only discovered when you try to run 
them. 

• Excellent string-handling capability - takes up 
to 26 string variables of any length. All strings 
can undergo all relational tests (e.g. 
comparison). The MicroAce also has string 
input to request a line of text when 
necessary. Strings do not need to be 
dimensioned. 

• Up to 26 single dimension arrays. 

• FOR/NEXT loops nested up 26. 

• Variable names of any length. 

• BASIC language also handles full Boolean 
arithmetic, conditional expressions, etc. 

• Exceptionally powerful edit facilities, allows 
modification of existing program lines. 

• Randomise function, useful for games and 
secret codes, as well as more serious 
applications 

• Timer under program control. 




PEEK and POKE enable entry of machine code 
instructions, USR causes jump to a user's 
machine language sub-routine. 

• High-resolution graphics with 22 standard 
graphic symbols. 

• All characters printable in reverse under 
program control. 

• Lines of unlimited length. 

'Excellent value' indeed! 

For just $149.00 (including handling charge)you 
get everything you need to build a personal 
computer at home.., PCB, with IC sockets for all 
ICs; case; leads for direct connection to a cassette 
recorder and television (black and white or color); 
everything! 

Yet the MicroAce really is a complete, powerful, 
full-facility computer, matching or surpassing other 
personal computers at several times the price. 

The MicroAce is programmed in BASIC, and you 
can use it to do quite literally anything, from playing 
chess to managing a business. 

The MicroAce is pleasantly straightforward to 
assemble, using a fine tipped soldering iron. It 
immediately proves what a good job you've done: 
connect it to your TV ... link it to the mains adaptor 
... and you're ready to go. 

Fewer chips, compact design, 
volume production-more power 
per Dollar! 

The MicroAce owes its remarkable low price to its 
remarkable design: the whole system is packed on 
to fewer, newer, more powerful and advanced LSI 
chips. A single SUPER ROM, for instance, contains 
the BASIC interpreter, the character set, operating 
system, and monitor. And the MicroAce 1K byte 



- a new generation of 
miniature computers 

A COMPLETE COMPUTER 
for $149.00 for 1K Kit 

Post and Packing FREE 

(Add 6% Tax for Shipments inside California) 

RAM (expandable to 2K on board) is roughly 
equivalent to 4K bytes in a conventional computer 
typically storing 100 lines of BASIC. (Key words 
occupy only a single byte.) 

The display shows 32 characters by 24 lines. 

And Benchmark tests show that the MicroAce is 
faster than all other personal computers. 

No other personal computer offers this unique 
combination of high capability and low price. 

The MicroAce teach-yourself 
BASIC manual. 

If the features of the BASIC interpreter mean 
little to you-don't worry. They're all explained in the 
specially-written book free with every kit! The book 
makes learning easy, exciting and enjoyable, and 
represents a complete course in BASIC 
programming-from first principles to complex 
programs. (Available separately-purchase price 
refunded if you buy a MicroAce later.) 
A hardware manual is also included with every kit. 

The MicroAce Kit: 

$149.00 with IK COMPLETE 

$169.00 with 2K 

Demand for the MicroAce is very high: use the 
coupon to order today for the earliest possible 
delivery. All orders will be despatched in strict 
rotation. If you are unsuccessful in constructing 
your kit, we will repair it for a fee of $20.00, post and 
packing FREE. Of course, you may return your 
MicroAce as received within 14 days for a full 
refund. We want you to be satisfied beyond all 
doubt and we have no doubt that you will be. 



280 A microprocessor 
chip, widely recognised 
as ihe best ever marie. 




■■■■■■■■■a 
■■■■■■■«■■ 
BiiiiiiiiBi; 



Your MicroAce kit 
contains... 

• Printed circuit board, with 
IC sockets for all ICs. 
Complete components set, 
including all ICs-all 
manufactured by selected 
world-leading suppliers. 
New rugged keyboard, 
touch-sensitive, wipe-clean. 
Ready-moulded case. 
Leads and plugs for 
connection to domestic TV 
and cassette recorder. 
(Programs can be SAVEd 
and LOADed on to a 
portable cassette recorder.) 
Mains adaptor of 600 mA 
at 9VDC nominal 
unregulated. 
FREE course in BASIC 
programming and user 
manual. 



JOIN THE REVOLUTION - DON'T GET LEFT 
BEHIND - ORDER YOUR MICROACE NOW!! 



Send Check, Money Order or quote your Credit Card No. to: 
MicroAce 1348 East Edinger, Santa Ana, California, Zip Code 92705. 
or phone (714} 547 2526 quoting your Credit Card Number. 



Quantity 



Description 



Unit Price 





MicroAce Kit 1K 


$149.00 






MicroAce Kit 2K 


$169.00 






Manual 


$10.00 






1K Upgrade Kit 


$29.00 




Shipmen 
add 6% 


Is inside California 
TAX 


TOTAL 





Amex. 
Diners 
Check 

Money Order 
Master Charge 
Visa 



Card No.. 



Exp. Date- 



Name. 



Address- 
City 



.Zip. 



Circle 164 on inquiry card. 



BYTE February 1981 239 



Text continued from page 222: 

collected onto the file specified in the 
initial command "filename". If this 
file already exists, it will be deleted. 
This allows the user to keep the basic 
data for processing at a later time. 
When completed, the user is returned 
to the option-selection level. Two 
possible errors may occur here: 

• "Disk or directory full". This 
means that you don't have enough 
room on the current disk to save all 
the data. Sorry, you will have to start 
over. Note that the storage space re- 
quired is 1 byte per column per line. 

• "No image was scanned". Here, 
you must scan an image before trying 
to file the data. 

H: Help Me 

The user can type H to view the 
whole menu again. Normally only 
the "option" line is printed. 

M: Set the Maximum and 
Minimum Values 

This option allows the user to 
specify what values are to be used in 
place of the actual maximum and 
minimum values in the data array. 
This is necessary when you want to 
print two separate pictures with the 
same character-substitution se- 
quence. (For example, this is the case 
when, due to its size, a picture was 
broken up into two or more sections.) 
The numbers are entered as decimal 
numerals in the range to 255. If the 
data is filed after making this change, 
the new maximum and minimum 
values will be permanent. 

P: Print the Data 

When you are ready to print the 
image, with the character- 
substitution array set and an image 
scanned, this option will give you 
time to change the paper and position 
the carriage by issuing the following 
message: 

Position paper (space) 

Hit the space bar when ready to 
begin. The program scales all of the 
light intensity levels stored so that the 
picture fits the length of character- 
substitution array entered. (Both the 
primary and secondary arrays are 
treated separately.) To terminate the 
printed listing prior to the actual end 
of the data, type any key. You are 
returned to the option-selection level. 



Listing 1 continued: 



0711 4045252423T0NE1 


DB 


'eEZ«lt;1*HI!7AXItN8»032I7*+(!',39,'-' 


,39,' ' 


072F 


DS 


34 




0751 40 INPUT2 


DB 


64 SECONDARY TONE ARRAY 




0752 1E NUHBR2 


DB 


30 JITS CURRENT LENGTH 




0753 2323232323T0NE2 


DB 


'HRHMMMI!!!!! ',39,' 


/ 


0771 


DS 


34 




0793 


DS 


&4 ;STACK AREA 




07D3 = STACK 


EQU 


« 





07D3 00 


MAX 


DB 





07D4 00 


HIN 


DB 





07D5 00 


LNGTH 


DB 





07D6 00 


LINES 


DB 





07D7 = 


BUFF 


EQU 


t 



THE F0LL0UING DATA IS SAVED ON THE FILE. 



;haxihuh value in array 
;hinihun value 
;line length 
jnuhber of lines 
;start data array here. 



0005 = 



CPU 



EQU 



;ENTRY to the system. 



07D7 




END 


100H 












042A AD1 


041C 


ADL00P 


03F3 


ASK 


0416 


AT0D 


06DD 


BADINP 


03C4 BADNUH 


044E 


BLP 


0434 


BT0A 


043E 


BT0A1 


0440 


BT0A2 


0454 BT0A3 


046C 


BT0A4 


0475 


BT0A5 


07D7 


BUFF 


03FD 


CHECK 


0005 CPM 


018C 


D01 


0197 


D02 


01A5 


D03 


0261 


11 


0283 D2 


028A 


D3 


01C2 


DELAY 


0259 


DIVLP 


027B 


DIVLP1 


02C6 ERR 


05B8 


ERRI 


02D1 


F1 


02A3 


FILE 


02DB 


FILELP 


03A9 GETNM1 


039C 


GETNUH 


047C 


HELLO 


0100 


IHAGE 


0709 


INBUFF 


017D INLP 


026D 


INLP1 


070F 


INPUT) 


0751 


INPUT2 


07D6 


LINES 


061 D LLNGTH 


07D5 


LNGTH 


07D3 


MAX 


062E 


MAXHIN 


064A 


MAXV 


07D4 HIN 


065A 


HINV 


05D4 


HSGI 


060E 


HSG2 


0677 


NFMSG 


034F N0FILE 


065F 


NONE 


0304 


NOTHING 


0708 


NSECT 


0710 


NUHBR1 


0752 NUHBR2 


0116 


OPT 


04B5 


OPTION 


0179 


0UTLP 


0269 


0UTLP1 


059F POS 


0245 


POUT 


040A 


PRINT 


024E 


PRINTLN 


0205 


PRT 


0212 PRTLP 


01DC 


PRTHX 


0581 


QUESTN 


0340 


READDN 


030F 


READF 


03CF READ 


0322 


READLP 


03D6 


RLP1 


03E5 


RLP2 


0707 


SCALE 


014C SCAN 


037D 


SETHAX 


06D0 


SETHN 


069F 


SETMX 


07D3 


STACK 


0711 TONE) 


0753 


T0NE2 


01CF 


TOUT 


035A 


TSET 


01 1 E 


UHAT 



w • cm 

MM* 

co mi \ 



s o * IN 

— n» ■» CM — 

• na»Hn 

■ nooniN 

ro co •» w rs. 



+ m rs \ i 

+ «• f~> \ * 4 

— 00 Pv s «• < 

CM GO CM M GO ( 



-HN 
I — M CO 



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240 February 1981 © BYTE Publications Inc 



yum/u. 






M1CR0 PR0C E 5S0R 

INTERFACE 
TECHNIQUES 



i 



r ly^Tnrnt. 




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Q: Quit and Return to CP/M 

This returns control directly to 
CP/M. If you want to save the col- 
lected data, this must be done prior to 
quitting the program. 

R: Read In the File 

The current disk will be searched 
for "filename. img", as specified in the 
initial command. If it is found, the en- 
tire data file will be read into 
memory. The maximum and mini- 
mum values associated with the data 
will be printed. If the file cannot be 
found, then an appropriate message 
will be printed and the user will be 
returned to the option-selection level. 

S: Scan a New Page 

The length of the scan line will be 



asked first. Type in the decimal num- 
ber of characters per line (1 to 255). 
You will be given a chance to position 
the paper before the scan is started. 
Hit the space bar to begin. The pro- 
gram will scan over the image in the 
print device until 255 lines have been 
scanned or a key has been hit. The 
maximum and minimum values read 
from the A/D converter are printed, 
and control is returned to the option- 
selection level. 

T: Set the Tone Array 

This is the heart of the processing 
system. For each column position, up 
to two characters will be typed to 
represent the A/D-determined inten- 
sity at this point. To accomplish this 
character substitution, two tone 



arrays are used. A primary tone array 
is always used and consists of up to 
sixty-four characters chosen by the 
user. They are entered in the order of 
maximum darkness to minimum 
darkness. (Minimum darkness is 
usually a space.) A secondary tone 
array can also be given for over- 
striking characters to achieve greater 
density variation. This array, if 
given, is generally the same length as 
the primary array, although this is 
not required. The program will deter- 
mine which character to use for any 
given value read from the A/D con- 
verter by the procedure: 

SCALE = (MAX-MIN)/N 
INDEX = (VALUE-MIN)/SCALE 
if INDEX > N-l then INDEX =N-1 

where: 

MAX = the maximum integer value 

in data. 

MIN = the minimum integer value 

in data. 

N = the integer number of 

characters in the tone array. 

VALUE = the integer value read 

from the A/D converter for this 

position. 

SCALE = the integer scale factor to 

use. 

INDEX = the integer index into the 

tone array (0 to N-l). 

The result of these computations 
(INDEX) specifies which of the N 
characters in the tone array will be 
used. A refers to the first (or maxi- 
mum density) character and (N-l) 
refers to the last available character 
(the minimum density). Note the 
value of (INDEX) is prevented from 
being greater than (N-l). 

Integer arithmetic is used for all 
computations and, as such, the num- 
ber of characters in the tone array 
affects the scale factor used. If the 
number of characters in the tone 
array is not an even divisor of the 
maximum-to-minimum variation, 
then the truncation that occurs in 
computing the scale factor has the 
effect of extending the minimum-den- 
sity character until the number is an 
even divisor. This can cause large 
blank areas to appear in the final 
printout. 

The tone arrays are entered using 
CP/M's buffered input routine. This 
means that all normal correction keys 
can be used on mistakes. Type a car- 
riage return to end the line. To skip 



242 February 1981 © BYTE Publications Inc 




Please send your free software catalog. 

(Check which software is of particular interest) 

D C COMPILER. Optimized native code for VAX 11/780, PDP-11, LSI-11, Z80, 
8085, 8080. Full C language as defined in Kernighan and Ritchie, with com- 
prehensive portable library. Cross compilers available. Runs under VMS, 
IAS, RSX-11D, RSX-11M, RSTS/E, RT-11, UNIX, Idris, CDOS, CP/M. From $600 

□ IDRIS OPERATING SYSTEM. System calls and file system identical to 
UNIX V6, including pipelines. Utilities include shell, editor, assembler, 
loader, archiver, compare, copy, grep, etc., plus system utilities for file 
system maintenance. Runs on LSI-11, PDP-11. From $1000. 

□ PASCAL COMPILER. Optimized native code for VAX 11/780, PDP-11, 
LSI-11, Z80, 8085, 8080. Full Pascal language as defined in Jensen and 
Wirth, with standard library. Includes C compiler and portable library, 
permitting intermixed C and Pascal. Cross compilers available. Runs 
under VMS, IAS, RSX-11D, RSX-11M, RSTS/E, RT-11, UNIX, Idris, CDOS, 
CP/M. From $750. 



Name. 



Company.. 

Street 

City 



.State. 



-Zip. 



Idris is a trademark of Whitesmiths Ltd. 
UNIX is a irademark of Bell Laboratories. 
CP/M is a trademark of Digital Research Co. 



VMS. RSX-11, RT-11. RSTS/E. VAX. 
PDP-11, LSI-11 are trademarks of Digital 
Equipment Corporation. 



Whitesmiths, Ltd. 

Software for srownups. 

(212)799-1200 

RO.B. 1132 Ansonia Station, New York, N.Y. 10023 



Prinary - "8EZi»;l*#B7AJ!«NBi032I7*+( ! '-' " 

Secondary-"««»#»«»«!! !!! 

Table 2: The primary and secondary image-tone character arrays, with high- 
intensity correspondence increasing from left to right. 



the secondary tone array, just type a 
return. This doubles the output speed 
but won't allow overstrike on certain 
characters. 

Setting the Tone 

To help me decide which characters 
to choose for the substitution arrays, 
I wrote a simple program (though it's 
not included here) that took the char- 
acter set as a dot matrix and looked at 
all overstruck combinations of two 
characters. The following algorithm 



was used to determine the resulting 
intensity from each combination: 

I(i,j,k,l)=RCI.[P(i,J,k) + {S(i,j,D 
-RCI*P(i,j,k)}] 

INTENSITY(k,l)=sum I(i,j,k,l), 
i = l to n, j = l to m 

where: 

INTENSITY(k,l)= intensity value 
for character "k" printed over 
character "1". 
P(i,j,k)= primary character num- 



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ber "k", row "i", and column "]". 

= 0, if this dot is not printed. 

= 1, if this dot is printed. 
S(i,j,l)= secondary character num- 
ber "1", row "i", and column "j". 

= 0, if this dot is not printed. 

= 1, if this dot is printed. 
RCI= ribbon condition index 
(range from 0.0 to 1.0). 
n = number of rows for character 
matrix. 

m= number of columns for char- 
acter matrix. 

Using this method, I checked all 
combinations of two characters and 
made a list ranging from maximum to 
minimum darkness. (There were 4560 
in all.) The resulting intensities 
ranged from (a space over a space) 
to 27 (a # on an @). To account for 
the results of typing one dot on top of 
another, an RBI (ribbon-condition in- 
dex) was used. It works like this: for a 
new ribbon (RBI = 1.0), two superim- 
posed dots are not blacker than one 
dot. However, for an older ribbon 
(RBI < 1.0), the second dot will result 
in a darker intensity. A value of 0.75 
for RBI seems about right for a nor- 
mal ribbon. The characters I use for 
the Teletype 43 are shown in table 2. 
Note that the quotes (") at the ends 
are used here as delimiters and should 
not be typed in. 

If your printer does not use a dot- 
matrix system, there are other ways 
to objectively judge character com- 
binations. Write a simple BASIC pro- 
gram to print out a character com- 
bination and then position the photo- 
transistor over this and read the result 
with the A/D converter. Or, of 
course, you could just guess. The 
characters listed in table 2 would be a 
reasonable place to start. Experimen- 
tation is the way to find the best 
character-substitution array for your 
own printer. 

Recognition of Images 

Pictures generated by this system 
are easier to recognize if they are 
"blurred" by moving the paper or 
your head rapidly, by squinting, or 
by viewing the object from a 
distance. This has the effect of reduc- 
ing the geometric distortion caused 
by the sudden change in contrast 
from one character to the next. Such 
blurring can be automated. A simple 
procedure would be to select the in- 
tensity value at a given point by 
averaging the points around it. This 
average value is then used when 



244 February 1981 © BYTE Publications Inc 





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Sold through authorized dealers and 
distributors only. OEM inquiries invited 



BYTE February 1981 245 



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selecting an appropriate character to 
print. Different amounts of blurring 
can be simulated by using more or 
fewer points in the averaging process. 
Obviously, the current program 
would have to be modified to accom- 
plish this. 

Area for Further Investigation 

Due to the digital form of the data, 
an area that would be interesting to 



look into is anamorphic art. This 
term refers to pictures that are greatly 
distorted (usually by some geometric 
procedure) and the original contents 
are difficult to recognize without 
transforming the image back by an 
appropriate means (like curved 
mirrors). A description and analysis 
of anamorphic art is contained in 
Martin Gardner's "Mathematical 
Games" noted in the references. 



Because the images are in digital 
form, transformation becomes a 
mathematical problem and not an ar- 
tistic one. I am sure that many en- 
thusiastic hobbyists can produce 
fascinating pictures along these lines. 

Running Under Another 
Operating System 

This program can be modified to 
run under most operating systems, in- 



246 February 1981 © BYTE Publications Inc 



H 



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N 
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BYTE February 1981 



247 



eluding cassette-tape systems, if the 
necessary system routines are pro- 
vided. The calling sequence for all 
CP/M functions is to specify the 
desired function by using the C 
register, loading any arguments using 
the DE register pair, and calling loca- 
tion 0005 (hexadecimal). Function 
results are returned in register A. The 
functions used by IMAGE are: 

• Function 1: Read a character from 
the keyboard. This routine will return 
a character (with bit 7 cleared) in the 
A register. If a character is not ready, 
it waits until it is. 

• Function 5: Print a character on 
the list device. The contents of the E 
register are sent to the printer. 

• Function 9: Print a message. The 
ASCII (American Standard Code for 
Information Interchange) character 
string pointed to by DE will be sent to 
the console device. A dollar sign ($) 
terminates the message. 

• Function 10: Buffered input. The 
register pair DE points to a character 
buffer that will contain a line typed 
by the user. The first byte must con- 
tain the maximum number of char- 
acters to be read; the second byte will 



be set to the actual number read (less 
the carriage return). The following 
space will be used to store the input 
characters (bit 7 cleared). 

• Function 11: Interrogate console 
status. This checks the status of the 
keyboard. If a character is ready to 
input (by function 1), the A register 
will be set to hexadecimal FF. Other- 
wise the A register is cleared. 

• Function 15: Open a file. For this 
call, DE points to a FCB (file control 
block) describing the file that will be 
opened. The program uses the default 
FCB built by the initial command 
processor within CP/M. The file is 
opened for either reading or writing 
unless the A register contains hexa- 
decimal FF, indicating that the file 
was not present. 

• Function 16: Close a file. Pointing 
DE at the FCB for the desired file will 
cause it to be closed. All I/O (in- 
put/output) must be completed. The 
directory will be updated. 

• Function 20: Read the next record. 
The next 128-byte record will be read 
from the file (DE points to the proper 
FCB). The data will be read into a 
buffer whose address is set with func- 
tion 26. On return, A will contain a 



Attention TRS-80 Mod II owners: 
P&T CP/M® 2 has more to offer! 



More Disk Storage 596K bytes with 
double densityon standard singlesided 
disk drives. If that's not enough, ver- 
sions are available for double sided 
expansion drives (1 ,2M bytes per disk) 
and the Cameo Hard disk system (1 0M 
bytes). 

More CRT Functions P&T CP/M 2 
has the most advanced screen driver 
available for the Mod II including: erase 
to end of line/screen, insert/delete 
line, cursor addressing, non-scrolling 
area on screen, and much more. 
More Serial I/O Capabilities The se- 
rial drivers in P&T CP/M 2 support 
ETX/ACK, XON/XOFF, and request to 
send handshaking. Direct control of 
the serial ports is also available for 
special applications. 



More Documentation We provide the 
standard CP/M manuals and our own 
150 page manual written specifically 
for P&T CP/M 2. 

More Utilities We have added 14 of 
our own utility programs for the Mod II 
to the standard CP/M utilities. 
More Useful System Functions P&T 
CP/M 2 has all sorts of useful features 
you won't find elsewhere: type-ahead 
buffer for keyboard input, system time 
ofdayclock, automatic program execu- 
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Prices 
Standard P&T CP/M 2 $ 1 85 

P&T CP/M 2 for Shugart 850 

2 sided drives $220 

P&T CP/M 2 forCameo Hard 

Disk system $250 



Wealso carrytheseothersoflware packages: 



Magic Wand text processor $350 

VEDIT text editor $110 

LYNC data communication program $95 

MCALL intelligent terminal program $65 

MAC macro assembler $90 

Pascal/M $175 

Microsoft Basic-80 Interpreter $325 

Microsoft Basic-80 Compiler $350 



CBASIC2 (improved performance) $105 
Osborn accounting software 
(requires CBASIC 2; manuals extra) 
each package $95: all four $295 
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CP/M is a trademark of Digital Research Inc. TRS-80 is a trademark of Tandy Corp. 



(if the transfer went properly) or a 1 
(if the end of the file was reached). 

• Function 21: Write the next record. 
The FCB pointed to by register pair 
DE indicates from which file the 128 
bytes are taken. The address of the 
data must be set by function 26. On 
return, the A register should contain 
0; anything else is interpreted by 
IMAGE as an out-of -space error. 

• Function 26: Set the DMA (direct 
memory access) address. The next 
disk read or write will reference data 
at the address specified by register 
pair DE. If this is never called, hexa- 
decimal 0080 will be assumed by 
default. 

So there's my system. It's simple, 
inexpensive, and leaves enough room 
for your creative modifications such 
as manipulating blurrihess, shadows, 
outlines, overstrikes, etc. The possi- 
bilities are myriad — how about using 
colored ribbons on your printer to 
obtain different overstrike hues? 
Whatever modifications you design, 
enjoyment is guaranteed. ■ 

References 

LBowden, J C and A K Scharschmidt. "Producing 
Pictures on Your Computer With a Diablo Printer." 
Dr Dobb's Journal of Computer Calisthenics & Or- 
thodontia, Volume 4, Number 39, Issue 9, October 
1979, pages 26 thru 29. 

2.Gonzales, R C and P A Wintz. Digital Image Pro- 
cessing. Reading MA: Addison-Wesley, 1977. 
3Gardner, M. "Mathematical Games: The Curious 
Magic ol Anamorphic Art." Scientific American, 
Volume 232, Number 1, January 1975, pages 110 
thru 116. 

4. Harmon L D. "The Recognition of Faces." Scien- 
tific American, Volume 220, Number 5, November 
1973, pages 70 thru 87. 

5.Hale JAG. "Dot Modulation for the Production of 
Pseudo Grey Pictures." Proceedings of the SID, 
Volume 17, Number 2, Second Quarter 1976, pages 
63 thru 74. 

6.McDonough T. "Computer Graphics With the 
Diablo." Creative Computing, Volume 5, Number 6, 
June 1979, pages 32 thru 35. 



For those readers who do not 
care to type in a program as long 
as the one in listing 1, the author is 
willing to provide source code on a 
floppy disk for $10. The disks will 
be IBM soft-sectored format, writ- 
ten in single density, and will be 
compatible with CP/M versions 
1.4 and 2.0. Contact: 

Clark A Calkins 

2564 Walnut Blvd §106 

Walnut Creek CA 94598 

Please allow 1 to 2 weeks for UPS 
delivery. 



248 February 1981 © BYTE Publications Inc 



Circle 167 on Inquiry card. 



Start learning and computing for only $129. 95 with a Netronics 8085-based 
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PC Board: Glass epoxy. plated through holes with 
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System Monitor (Terminal Version): 2k bytes of 
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change all registers . . . single step with register display 
at each break point, a debugging/training feature . - ■ go 
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constant . . . display blocks of memory . . . automatic 
baud rate selection to 9600 baud . . . variable display 
line length control (1-255 characters/line) . . . chan- 
nelized I/O monitor routine with 6-bit parallel output 
for high-speed printer . . . serial console in and console 
out channel so that monitor can communicate with I/O 
ports. 

System Monitor (Hex Keypad/Display Version): 
Tape load with labeling . . . tape dump with labeling 
. . . examine/change conlentsof memory . . . insert data 
. . . warm start . . . examine and change all registers . . . 



(Also available wired & tested, $1799.95) 




Full 8" disk system for less than the price of a mini (shown with 
Netronics Explorer/85 computer and new terminal). System features 
floppy drive from Control Data Corp., world's largest maker of 
memory storage systems (not a hobby brand.') 




single step with register display at each break point . . . 
go to execution address. Level "A" in this version 
makes a perfect controller for industrial applications, 
and is programmed using the Netronics Hex Keypad/ 
Display, II is low cost, perfect for beginners. 
HEX KEYPAD/DISPLAY SPECIFICATIONS 
Calculator type keypad with 24 system-defined and 18 
user-defined keys. Six digit calculator- type display, 
that displays full address plus data as well as register 
and status information. 
LEVEL "B" SPECIFICATIONS 
Level "B" provides the S-100 signals plus buffers/ 
drivers to support up to six S-100 bus boards, and in- 
cludes: address decoding for onboard 4k RAM expan- 
sion selectable in 4k blocks . . . address decoding for 
onboard 6k EPROM expansion selectable in 6k blocks 
. , . address and data bus drivers for onboard expansion 
. . . wait state generator(jumper selectable), to allow the 
use of slower memories . . . two separate 5 volt regula- 
tors. 

LEVEL "C" SPECIFICATIONS 
Level "C" expands Explorer/65's motherboard with a 
card cage, allowing you to plug up to six S-100 cards 
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number of S-100 connectors. 




LEVEL "D" SPECIFICATIONS 

Level "D" provides 4k of RAM power supply regula- 
tion, filtering decoupling components and sockets to 
expand your Explorer/85 memory to 4k (plus the origi- 



nal 256 bytes located in the 8155A). The static RAM 
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blocks. 

LEVEL "E" SPECIFICATIONS 
Level "E" adds sockets for 8k of EPROM to use the 
popular Intel 2716 or the TI 2516. It includes all sockets, 
power supply regulator, heat sink, filtering and decou- 
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RAM IC's (allowing for up to 12k of onboard RAM). 
DISK DRIVE SPECIFICATIONS 

• 8" CONTROL DATA CORP. • Data capacity: 401,016 bytes 
professional drive, (SD), 802,032 bytes (DD), 

• LSI controller. unformatted. 

• Write protect. • Access time: 25ms (one 

• Singleordoubledensity. track). 
DISK CONTROLLER/ I/O BOARD 
SPECIFICATIONS 

• Cont.-ols up to four fl" drives. • 2716 PROM socket included 

• 1771 A LSI (SD) floppy disk for use in custom 
controller. applications. 

• Onboard data separator • Onboard crystal controlled. 
(IBM compatible). • Onboard I/O baud rate 

• 2 Serial I/O ports generators to 9600 baud. 

• Autoboot to disk system • Double-sided PC board 
when system reset. (glass epoxy, ) 

DISK DRIVE CABINET/POWER SUPPLY 

• Deluxe steel cabinet with individual power supply for max- 
imum reliability and stability. 

ORDER A COORDINATED 
EXPLORER/85 APPLICATIONS 
PAK! 

Beginner's Pak (Save $26.00!) — Buy Level "A" (Ter- 
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Keypad/Display. Intel 60B5 User Manual, Level "A" 
Hex Monitor Source Listing, and AP-1 5-amp Power 
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PRICE: $219.93 plus post. & insur. 
Special Microsoft BASIC Pak (Save $103,001)— In- 
cludes Level "A" (Terminal Version). Level "B". 
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ADD A TERMINAL WITH CABINET, 
GET A FREE RF MODULATOR: Save 
over $114 at this SPECIAL PRICE: $499.9$ 
plus post. & insur. 
Special 6" Disk Edition Explorer/83 (Saveover$104l) 
— Includes disk-version Level "A", Level "B", two 
S-100 connectors and brackets, disk controller, 64k 
RAM, AP-1 5-amp power supply, Explorer/85 deluxe 
steel cabinet, cabinet fan, 8' SD/DD disk drive from 
famous CONTROL DATA CORP. (not a hobby 
brand!), drive cabinet with power supply, and drive 
cable set-up for two drives. This package includes 
everything but terminal and printers (see coupon for 
them). Regular price $1630.30. all yours in kit at 
SPECIAL PRICE: $1499.9$ plus post. & insur. Wired 
and tested, only $1799.95. 

Special! Complete Business Software Pak (Save 
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General Ledger. Accounts Receivable. Accounts 
Payable. Payroll Package: (regular price S1325). yours 
now at SPECIAL PRICE: $699.95. 



Please send the items checked below: 
D Expl0rer/85 level "A" kH(Terminal Version). . . $129.95 plus 

$3 post. & insur. 
D Explorer/83 level "A" Idt (Hex Keypad/Display Version) . . . 

$129.9$ plus S3 post. & insur. 
□ Bk MlCrOSC-fl BASIC on cassette tape. $64.95 postpaid. 
O 8k Microsoft BASIC In ROMIdt [requires Uvels "B", "D" and 

"E") . . . $99.95 plus 12 post. & insur. 
D Level "8" (S-100) Idt. . . $49.95 plus $2 post. & insur. 
D Level "C" (S-100 6-card expander) ki t $39.95 plus $2 past. 

& insur. 
D level "D" (4k RAM) Idt ... $69.95 plus S2 post. & insur. 
D level "E" (EPROM/ROM) Idt . . . $5.95 plus 50« p&h. 
D Deluxe Steel Cabinet for Explorer/85... $49.95 plus $3 post. 

& insur. 

□ Fan For Cabinet . . . $I5.00plus SI 50 post. & insur. 

D ASCII Keyboard/Computer Terminal kit: features a full 12s 

character sel. u&l case: full cursor control: 75 ohm video 
output: convertible to baudot output: selectable baud rale. 
RS232-C or 20 ma. I/O. 32 or 54 character by 16 line formats, 
and can be used with either a CRT monitor ora TV set (if you 
have an RF modulator) . . . $149.95 plus $3.00 post. & insur. 
D Deluxe Steel Cabinet for ASCII keyboard/terminal . . . 
$19.95 plus S2.50 post. & insur. 

D New! Terminal/Monitor: (See photo) Same features as above, 
except 12" monitor with keyboard and terminal is in deluxe 
single cabinet: kit . . . $399.95 plus S7 post. & insur. 

D Hazelllne terminals: Our prices loo low to quote— CALLUS 

D Iear-Slgler terminals/printers: Our prices loo low to quote: 
CAULS 

D Hex Keypad/Display Idt ... $69.95 plus S2 post. & insur. 



D AP- 1 Power Supply Kll ±8V ® 5 amps) in deluxe steel cabinet 

. . . $39.95 plus S2 post. & insur. 
D Gold Plated S-100 Bus Connectors . . . $4.85 each, postpaid. 

□ RF Modulator HI (allows you to use your TV set as a monitor) 

. . . $8 95 postpaid. 

D 16k RAM Idt (S-100 hoard expands to64k). . . $l99.95plusS2 

post. & insur. 
O 32k RAM kit. . $299.95 plus $2 post. & insur. 
a 48k RAM kit.. . $399.95 plus $2 post. & insur. 
D 64k RAM kit $499.95 plus $2 post. & insur. 
D 16k RAM Expansion kit (to expand any of the above in 16k 

blocks up to 64k) . . . $99.95 plus $2 post. & insur. each. 

D Intel 8065 cpu Users' Man ml. . . $7.50 postpaid. 

D 12" Video Monitor (10MHz bandwidth) . . . $139.95 plus $5 
post. & insur. 

□ Beginner's Pak (see above) $189.95 plus S4 post. & insur. 

D Experimenter's Pak (see above) . . . $219.95 plus $6 post. & 
insur. 

D Special Microsoft BASIC Pak Without Terminal (seeahovo|. . 

$329.95 plus S7 post. & insur. 

D Same as above, plus ASCII Keyboard Terminal With Cabinet, 
Gel Free RF Modulator (see above) . . . $499.95 plus $10 post. 
& insur. 

O Special 8" Disk Edition Explorer/85 (sen above) . $1499.95 

plus $26 post. & insur. 

O Wired t, Tested $1799.95 plus $26 post. & insur. 
D Extra 8" CDC Floppy Drives . . . $499.95 plus $12 posl. & insur. 
D Cabinet £ Power Supply For Drive . . $69.95 plus $3 post. & 

insur. 

D Drive Cable Sei-up For Two Drives ... $25 plus $1.50 post. & 



. $199.95 plus $2 post. 



D Disk Controller Board With I/O Pons . 

& insur. 

D Special: Complete Business Software Pak (see above) . . . 

$689.96 postpaid. 

SOLD SEPARATELY: 
DCP/MI.4. .. $100 postpaid. 
'J CP/M 2.0... $l50poslp,iid. 
D Microsoft BASIC. . . $325 postpaid. 
D Intel 8085 cpu User Manual . . $7.50 postpaid. 
D level "A" Monitor Source listing ... $2$ postpaid. 
^m Continental U.SA Credit Card Buyers Outside Connecticut ^ 

I CALL TOLL FREE: 800-243-7428 m 

^H To Order From Connecticut Or ForTechnical I^V 
^ Assistance, call (203) 354-9375 ^ 

Total Enclosed (Conn res. add sales tax) S 

Paid By: 

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■^ NETRONICS Research & Developmenl Ltd. 
ISA 333 Litchfield Road, New Mllford, CT 06776 



Southern California 




r 
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Q. 

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Southern Calif ornia— a mecca for 
engineers— is rallying in anticipation 
of a booming business economy 
because of increased military 
spending expected under the new 
Reagan administration. The result is 
that the demand for 
electrical/electronic, computer 
science, data communications or 
aerospace/aeronautical engineers in 
the Golden Gate State has never been 
better. 

As one engineer working in 
Southern California recently 
remarked, "If an engineer doesn't like 
the job, he or she can literally walk 
across the street to another one." 

The hub of Southern California's 
aerospace activity is located in Los 
Angeles County, Orange County, and 
San Diego County, areas which in 1980 
utilized the talents of 55,859 



engineers. This year, according to 
economists, an additional 15,040 will 
be required by the high-technology 
companies that need them. 

With 40% of the total aerospace 
population employment in the United 
States located in Southern California, 
New England, another high technology 
area, runs a distant second, providing 
14% of the nation's aerospace 
engineering employment. Southern 
California will continue to outshine the 
rest of the nation in this industry 
during the 1980s because of two 
reasons: 

1. The projected spurt in defense 
spending by the Reagan 
administration. 

2. The construction of commercial, 
fuel-efficient jet aircraft that will be 
sold here and abroad. 

A spokesman for a major aircraft 



manufacturer says, "There's talk of a 
new military bomber, either the B-1 or 
another one. There is even the 
possibility that the MX missle program 
may be sited for our state, and that the 
cruise missile program will be 
accelerated. The Polaris, a 
submarine-launched missile, may also 
be built here." 

Another engineer at the plant of a 
major aircraft manufacturer confided, 
"Because Reagan is homegrown, we 
hope he'll let us build the B-1 bomber 
here." He added that in addition to the 
need for aerospace engineers, there 
are also great opportunities for those 
interested in alternative energy 
sources. 

The reason is that tax 
credits of 25% to 50% are awarded to 
anyone who installs solar heating. 
Approximately 100,000 solar-heated 



250 BYTE February 1981 





homes and businesses exist in the 
Golden Gate State. Obviously 
Southern California is a hot market for 
this field, which is growing in 
importance. 

The computer business is also 
booming, and companies are scouring 
the country seeking engineers with the 
qualifications necessary to develop 
the high technology products we need 
for tomorrow. 

In addition to the progressive 
scientific climate, the weather in 
Southern California is "the closest 
thing to perfect," according to the 
United States Weather Bureau. The 
average temperature isasunny71 
degrees, with only 1 4 inches of rain a 
year, falling mostly between 
November and March. ("It never rains 
in Southern California," so the song 
goes.) The proximity of the ocean, the 



desert, and the mountains makes it 
possible to ski, bask in the desert sun, 
and swim in the Pacific ocean, all in the 
same day. 

Southern California's standard of 
living is one of the highest in the 
nation: the median family income in 
Orange County in 1980, for example, 
was $29,000. Los Angeles families 
averaged $26,000, Santa Barbara, 
$27,000, and San Diego households 
took home $24,000. But the Catch-22 
on housing is that the median price 
was a whopping $100,000, and this 
substantial rate is exacerbated (if not 
caused) by a housing shortage and 
high interest rates. Businesses 
employing engineers are, in some 
instances, trying to circumvent this 
problem by paying part of the interest 
rate on the mortgages of employees 
that relocate. For example, if the 
mortgage rate is 14%, the company 
may pay 4% of the cost. 

To help ease the housing problem, 
business-oriented Lieutenant 
Governor Michael Curb has 
assembled a task force of real estate, 
government, and labor officials. He 
blames rent control for the shortage 
because he says it discourages 
construction of new housing. 

"If we could increase the supply of 
houses, demand would diminish, and 
so would prices," an aide says. He 
adds, "Average personal income in the 
state is the highest in the country; it's 
$9,900 compared with a national 
average of $8,700. Housing is the only 
major stumbling block to an otherwise 
excellent quality of life." 

He concludes, "Today business is 
no longer a dirty word. It's a four letter 
word meaning jobs." 

This statement is borne out by 
recent figures that show that 
California will continue to grow at a 
rate of 30% to 50% through the 
mid-'80s. Economists in the state 
predict that there will be 300,000 new 
jobs needed for manufacturing in the 
next few years, a sure sign of the 
state's vibrant economy. 

Another advantage of living and 
working in Southern California is that it 
offers engineers the opportunity to 
continue their education. The 
University of California at San Diego, 
for example, boasts three Nobel Prize 
winners on its staff and 36 members of 
the National Academy of Sciences. 

California Institute of Technology in 
Pasadena is another first-rate school 
for engineers. 

In addition, many of the high 




California's Lt. Governor, Mike Curb, 
is working with a task force of real 
estate, government, and labor officials 
to help ease the housing problem. 

technology companies in Southern 
California offer their employees 
in-house courses. In some cases 
engineers are updated in their 
specialties through the use of 
closed-circuit television beamed from 
schools in other parts of the state. 

Most companies encourage their 
engineer employees to upgrade their 
skills, and many pay full or partial 
tuition. 

To sum up, the demand for 
engineers in beautiful Southern 
California in this decade is expected to 
remain strong. The salaries are high, 
the work is both exciting and 
important, and industry is hiring at an 
accelerated rate. In addition, the 
Golden Gate State offers a lifestyle 
with every kind of cultural and 
recreational activity available 
anywhere in the world. 

As one Southern California 
economist put it, "Where are all those 
engineers? We need them." 

If you area recent graduate or a 
veteran engineer seeking a virtually 
unlimited future, the Golden Gate 
State offers an opportunity that you 
may never have again. If you are 
serious about your career, are an 
electrical/electronic, computer 
science, data communications, or 
an aerospace/aeronautical engineer, 
don't miss the following Southern 
California Career Opportunities 
Section featuring blue-chip companies 
that are interested in you and your 
talents now and in the future. 

—John Brand 



> 

Q. 

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BYTE February 1981 



251 



SOUTHERN CALIFORNIA CAREER OPPORTUNITIES 



Who will be first 
with the avionics 
of the 21st century? 



It could be you and Hughes Radar 
Systems. 

We pioneered pulse Doppler radar 
and built the first operational airborne 
programmable signal processor. Today, 
three out of the four front-line U.S. 
tactical aircraft have Hughes radars. 
We're leaders in synthetic aperture 
radar, in-weather reconnaissance and 
strike radar, high order language, 
antenna arrays and holographic 
displays. We're even building the 
rendezvous radar for the Space Shuttle. 

And with computer-aided design, 
manufacturing, and testing of intelligent 
radar devices, the future is at Hughes. 



In fact, Hughes is one of the nation's 
largest employers of electronic 
engineers and a major employer in 
virtually every other scientific, computer 
and technical discipline — with 1,500 
projects and a backlog of over $5 
billion. Yet we're decentralized to give 
you the kinds of environments that 
stimulate innovation and promote 
recognition of your work. 

Who will be first with the avionics of 
the future? It could be you and Hughes. 

At Hughes Radar Systems, we'll 
introduce you to people, ideas and jobs 
that could change your world. And 
maybe ours. 



It could be you and Hughes 

Radar Systems. 



Call (213) 647-4900, collect, or send 
resume to: 

Engineering Employment 

Dept. B2 

Hughes Aircraft Company 

Radar Systems Group 

P.O. Box 92426 

Los Angeles, CA 90009 

Current openings: 

Software Design/Analysis 
Software Test Engineering 
Systems Integration & Test 
Computer-Aided Design & 

Manufacturing 
RF/ Microwave Design 
Digital Circuits Design & Test 
Radar Systems Design 
Large Scale Integration Design, 

Development & Test 
Production Process Engineering 
Microprocessor Development/ 

Applications 
Antenna Systems Design & Test 
Reliability Engineering 
Production Test Engineering 
Industrial Engineering 



HUGHES AIRCRAFT COMPANY 

RADAR SYSTEMS 

Proof of U.S. Citizenship Required 
Equal Opportunity Employer 




252 BYTE February 1981 



Circle 168 on inquiry card. 



Product Review 



The Heath H-14 Printer 



Bradford E Rehm, 1004 Middle Cove Dr, Piano TX 75023 



What this country needs is a good $250 printer. It 
ought to accept characters at 9600 bps (bits per second) 
and print them at 100 lines per minute. It should produce 
letter-quality print in various formats, including 80, 96, 
and 132 columns per page and 6, 8, or 10 lines per inch. It 
should have graphics capabilities, and it should offer an 
adjustable tractor-feed mechanism that can use narrow or 
wide paper. It should be very reliable, easy to service, 
quiet, and pleasing to look at. 

Has Heath given us the Ail-American line printer? 
Perhaps not, but the folks in Benton Harbor, Michigan, 
have chalked up real accomplishments in several areas. 
As a $595 kit, the H-14 comes closer than any other 
80-column impact printer on the market (at this writing) 
to meeting the price criterion. The somewhat higher 
"assembled" price still falls below most of its competitors' 
prices. And the H-14 does this while making a fine show- 
ing in the area of capabilities. 

The H-14 Kit 

The kit version of the printer is somewhat intimidating 
because of the sheer number of parts that emerge from 
the shipping carton. Rumors have been circulating to the 
effect that Heath had simply built electronics around an 
imported printer mechanism or that they had built a new 
enclosure around a familiar American-made mechanism 
which uses the Practical Automation dot-matrix print 
head. The truth is that while Heath uses the Practical 
Automation DM-101 print head, the rest of the 
mechanism (except, of course, for the driver motors) is of 
Heath's own design. 

The builder, at any rate, assembles the printer 
mechanism from the very beginning. Happily, it is sur- 
prising to discover how easy the assembly is to execute, 
because, as always, Heath has done an outstanding job of 
preparing the kit manual. In fact, it is hard to believe that 
Heath charges $300 more for the assembled version. 

There are few special parts in the mechanical portion of 
the printer. Two of the four shafts that operate the 
sprocket feed and support the print head, for example, 
are standard, quarter-inch extension shafts. This allows 
use of common quarter-inch bushings, collars, and grom- 
mets, which not only contributes to the low cost of the 
device, but also makes maintenance simpler. 

Heath chose a more expensive route in providing a 
substantial die-cast metal base upon which the printer is 
built. It forms the lower half of the housing and supports 
the print-head mechanism, power transformer, and 
printed-circuit board. Although the molded plastic cover 
of the device is very light (why not, since it supports 
nothing), the metal base gives the H-14 the hefty, stay- 
put feel of a heavy-duty piece of equipment. 



The Electronic Circuitry 

Nearly all of the parts in the electronics portion of the 
H-14 are mounted on two printed-circuit boards. The 
main board is busy but by no means crowded, and there 
are two extra LEDs (light-emitting diodes) available for 
checking logic functions as the integrated circuits are in- 
stalled. The second, smaller board, which corrects a 
design oversight and which was not initially shipped with 
the kit (original shipment, February 1979), is mounted 
adjacent to the paper-drive motor. 

The circuit is assembled on a double-sided, 12.5 by 
25.5 cm (4% by 10 y 8 inch) board which includes the 
power-supply rectifier diodes, the printer-data-handling 
electronics, and the print-head and motor-driver circuits. 
The power-supply filters, a low-voltage regulator and a 
series-pass transistor, and an end-of-paper sensor are 
mounted off the board. 

Because a microprocessor-controller is used, the cir- 
cuitry is straightforward. Data enters and leaves the 
printer through a pair of EIA or 20 mA current-loop in- 
terfaces. These are connected to a UART (universal asyn- 
chronous receiver/ transmitter) that provides the inter- 





Name 


matrix, impact); ASCII 


H-14 


96-character set; 75 




cps maximum print 


Manufacturer 


speed (40 cps average); 


Heath Company 


80-, 96-, or 


Benton Harbor MI 


132-column line width, 


49022, (800) 253-0570 


software selectable; ac- 




cepts 2V2- to 9 Vi -inch- 


Dimensions 


wide paper, fan-folded 


Height: 12.2 cm (4 3 /« 


sprocket-feed only 


inches); Width: 46.5 




cm (18% inches); 


Software 


Depth: 36.2 cm (14 13 / 16 


Requires H-8-14, 


inches) 


H-8-17, or H-8-18 soft- 




ware for use with 


Price 


Heath H-8 computer 


$595 kit; $895 


or HT-11 software for 


assembled 


use with Heath H-llA 




computer 


Features 




Controlled by Fair- 


Hardware Options 


child F8 microproces- 


Serial interface via 


sor; uses Practical 


RS-232 or 20 mA cur- 


Automation DM-101 


rent loop, 110 to 4800 


print head (5 by 7 dot- 


bps 



February 1981 © BYTE Publications Inc 253 



Circle 169 on inquiry card. 



INTRODUCING THE 
LDP1 8088 MAINFRAME 

Want to move to the new 16 bit generation of micro's? You do 
not want to assemble a system from board products? Finally, a 
complete system that only needs a Video Terminal plugged in 
to be on the air. 

The LDP1 will get you going with your 16 bit systems quickly 
while not obsoleting other boards in your system. The LDP1 is 
a 16 bit system based on the LDP88, 8088 CPU board and the 
LDP72. advanced floppy disk controller. In addition you get 
64 K of RAM, an 8" floppy disk, a mainframe with power supp- 
ly and your choice of two different operating systems. All this 
for the unbelievable price of $3499 (with 86-DOS). And to make 
a good deal better, if ordered before February 28th, you pay 
only $2995 (with 86-DOS). 





PRICES 


BEFORE FEB. 28 


LDP1 with 86-DOS 


$3499 


$2995 


LDP1 with CP/M-86 


3599 


3099 




Kit 


Assembled & Tested 


LDP88 


$349.95 


$399.99 


LDP72 


219.95 


274.95 


S100 Prototype Board 


29.95 




86-DOS 


195.00 




CP/M-86 


250.00 




Microsoft Basic 86 


500.00 


86-DOS required 




350.00 


with LDP1 and 86-DOS 


PASCAL/M 


250.00 


CP/M-86 required 



Rev. A LDP88's while they last $275 



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face between the serial communication lines and the 
parallel data bus of the microprocessor. The latter is a 
descendant of Fairchild's F8 family and includes on-chip 
read-only memory. This custom-masked device holds the 
program which enables the microprocessor to operate the 
printer. Data storage and address latching (which helps 
the processor interleave I/O [input/output] and printing 
tasks) are handled by a pair of 2112 memory devices and 
a 74LS273 8-bit latch. The processor also has four 8-bit 
I/O ports which are used as follows: two drive the seven 
print-head solenoids, the head-drive motor, the ribbon- 
drive motor, and the paper-drive stepper motor; another 
does I/O to the UART; and the remaining one selects the 
specific device which is being driven. 

Two Interesting Circuit Details 

Two other sections of the circuit merit attention. 
Asked about how Heath was able to make the Practical 
Automation print head operate at speeds in excess of 
120 cps (characters per second) while other printers using 
the same head have been restricted to lower speeds, an 
engineer at Heath explained that the H-14 continually 
monitors the resistance of one of the head magnet coils. 
In light-duty printing, the coil temperature does not rise 
significantly. During long printing jobs or when using the 
compact 132-column print, the internal temperature will 
rise to the point at which the head could be damaged. The 
increased temperature also increases the resistance of the 
winding, however, so a simple bridge circuit, monitored 
by two op amps, is used to detect the change and briefly 
halt printing. 

On learning about this trick, one wonders if the printer 
will spend most of its time cooling down after it reaches 
operating temperature. In practice, however, this ar- 
rangement works well. The H-14 printed eight to fifteen 
80-column pages before pausing to cool. The number of 
pages it executes seems to depend mainly on the ambient 
air temperature and circulation. Heath has left a slot in 
the bottom plate to provide cooling air from below, 
which can exit through the paper-viewing slot in the top 
cover, so the Heath engineers clearly understand that air 
circulation affects throughput. 

That large rectangular slot in the bottom plate, just 
below the print head, is surrounded by a row of small 
holes. Some H-14 owners will visualize a blower and 
bellows arrangement fastened to the bottom plate at a 
flange bolted at these holes. It is surprising that they are 
not there for that reason at all. Although the printer is 
not certified by the US Underwriters' Laboratories, it has 
been approved by the latter's Canadian counterpart. The 
row of holes is necessary so that the H-14 can pass a test 
in which flaming oil poured into the enclosure must be 
quenched as it exits from the ventilation slot on the bot- 
tom plate. (Isn't it good to know your H-14 can be used 
as a flaming-oil quencher!) 

The number of pages which can be printed before the 
first cool-down pause is smaller, of course, when the 96- 
or 132-column print format is selected. The duty cycle of 
the head is increased in these modes — laying down 96 
characters in a line before taking a breath (while going to 
the next line starting position) is more taxing than print- 
ing only 80 characters before taking a line break. Never- 
theless, the pauses the H-14 takes for head cooling are not 
long. Again, the time required depends upon the ambient 
air temperature, but I find that most pauses are on the 



254 February 1981 © BYTE Publications Inc 



Circle 170 on Inquiry card. 



From Digital Research 




The Best 
Gets Better 

CP/M®, the industry standard, 
continues to expand, because your 
needs continue to expand. 

CP/M-80™ 

For cost-effective computing on 8-bit 
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For jobs that require more address 
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CP/M. It's available on over 250 
types of computers. For a closer 
look, ask your dealer, your manu- 
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U.S.A. 

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IQ DJGJTflL RESEARCH* 




Circle 171 on inquiry card. 



BYTE February 1981 255 




S-100 GRAPHICS 







Unretouched photograph 

• TEKTRONIX EMULATOR 

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Send for brochure and data. 

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(617)926-0869 



order of two to five seconds, and they occur, nominally, 
every two to five lines after an eight- to fifteen-page 
warm-up period. 

How closely does the H-14 approach the thermal limits 
of the print head in this kind of operation? A call to Prac- 
tical Automation in Shelton, Connecticut, yielded the in- 
formation that the DM-101 head can be operated at 
100 cps (characters per second) bidirectionally if suffi- 
cient forced-air cooling is available. Continuous bidirec- 
tional operation above 16.5 cps is not recommended 
without forced ventilation or other protection, and the 
maximum internal operating temperature of the head is 
62° C. 

Heath claims that the temperature threshold for the 
shutdown has been set at approximately 50° C, which is 
well within the Practical Automation specification. This 
suggests that the printer can be run for long periods 
without fear of overheating the head. If you should want 
to try this, by the way, you may want to make sure that 
the head nose bearing has adequate lubrication. There is 
a felt-pad oil retainer on the back of the unit which 
should normally be given a few drops of machine oil after 
running through five boxes of paper. Giving it a drop or 
two before printing a whole box nonstop would be pru- 
dent. 

There is no way to directly lubricate the solenoid- 
operated wires that actually do the printing. As is true for 
most wire-matrix heads, the wires are continuously 
lubricated by ink in the ribbon. This means that if you in- 
tend to realize the full, 100-million-character life of the 
H-14's head, you will never want to run the printer with a 
dry ribbon or without paper. You will also want to use 
only nylon ribbons, since cloth ribbons are easily per- 
forated by the head wires. 

Practical Automation recommends that nylon ribbons 
containing oil-based ink be used. A Heath representative 
that I contacted could not confirm that the office- 
equipment-type ribbon Heath supplies contains an oil- 
based ink. Testing at Heath has shown, however, that 
maximum head life is possible with its ribbons. (The 
manufacturer of one of the leading brands of ribbons 
available in office-supply stores was also contacted in an 
attempt to learn whether the ink used in these products is 
oil-based. In spite of the best efforts of the company's 
Dallas office, we were not able to acquire the informa- 
tion.) 

The other interesting circuit is the driver for the paper- 
feed motor. There was a note in the original instruction 
manual for the H-14 saying that Heath would provide, 
upon request, a modification kit to enable the printer to 
more reliably lift paper from a box placed on the floor 
below it. The problem addressed occasionally appeared 
when my H-14 was required to lift 20-pound paper. The 
paper-drive stepper motor would occasionally growl and 
feed the paper in fractional-line increments instead of a 
full line. 

The original stepper drivers used 7416 open-collector 
inverter/buffer devices to interface the microprocessor 
port to transistors that switched the motor on and off. 
One side of each winding was pulled high by a 12 V 
supply, while the other was pulled low by a transistor. A 
step was executed by turning off a pair of transistors. The 
problem was that the motor did not develop enough 
torque with a 12 V supply, but a higher voltage would 
probably have overheated it (stepper motors consume 



256 February 1981 © BYTE Publications Inc 



Circle 172 on Inquiry card. 



DYNACOMP 



Quality software for : 

ATARI 

PET 

APPLE II Plus 



TRS-80 (Level II)* 
NORTH STAR 
CP/M 8" Disk 



GAMES, SIMULATIONS and EDUCATION 



BRIDGE 2.0 (Available for all computers) 



Prke: S17.95 Cassette 
121.95 Diskette 

An all-inclusive version of this mosl popular of card games. This program both BIDS and PLAYS eilhci contract or 
duplicate bridge. Depending on the contract, your computer opponents will either play the offense OR defense. If you bid 
loo high, the computer will double your contract! BRIDGE 2,0 provides challenging entertainment foi advanced playeis 
and 'is an eicellenl learning tool for the bridge novice. 

HEARTS 1.5 (Available for all computers) Prke: $14.95 Cassette 

$18.95 Diskette 

An exciting and entertaining computet version or this populat card game. Hearts is a trick-oriented game in which the 
purpose is not to lake any hearts or the queen of spades. Play against two computer opponents who are atmed with hard- 
to-beat playing strategies. 

VALDEZ (Available for all computers) Price: S14.95 Cassette 

$18.95 Diskette 

A simulation of supertanker navigation in the Prince William Sound and Valdcz Narrows. The program uses an extensive 
256X256 element radar map and employs physical models of ship response and tidal patterns. Chan your own course 
through ship and iceberg traffic. Any standard terminal may be used for display. 



FLIGHT SIMULATOR (Available for all computers) 



Price: S17.95 Cassette 
S21.95 Diskette 

:malicat simulation of take-off, flight and landing. The program utilizes aerodynamic equa- 
f a rial airfoil. You can practice instrument approaches and navigation using radials and 
compass headings. The more advanced flyer can also perform loops, half-rolls and similar acrobatic maneuvers. 

CR1BBAGE 2.0 (TRS-80 only) Prke:S14.95 Cassette 

S18.95 Diskette 
This is a well-designed and nicely executed two-handed version of the classic card game, cribbagc. It is an excellent pro- 
gram for the cribbagc player in search of a worthy opponent as well as the beginner wishing to learn the game, in par- 
ticular the scoring and jargon. The standard cribbagc score board is continually shown at the top of the display (utilising 
the TRS-BO's graphics capabilities), with the cards shown underneath. The computer automatically scores and also an- 

CHESS MASTER (North Star and TRS-80 only) Prke:S19.95Cassc((e 

523.95 Diskette 
This complete and vciy powerful program provides live levels of play. It includes castling, en passant captures and the 
ptomolion of pawns. Additionally, the board may be preset before the start of play, permitting the examination of 
"book" plays. To maximize execution speed, the program is written in assembly language Iby SOFTWARE 
SPECIALISTS of California). Full graphics ate employed in thcTRS-80 vetsion. and two widths of alphanumeric display 
todate North Star users. 



STARTREK 3.2 (Available for all computers) 



Prke: S 9.95 Cassette 
S13.95 Diskette 

This is the classic Starlrek simulation, but with several new features. For example, the Klingons now shoot at the Enter- 
prise without warning while also attacking starbases in olhet quadiants. The Klingons also attack with both light and 
heavy cruisers and move when shot at! The situation is hectic when the Enterprise is besieged by three heavy cruisers and a 
starbasc S.O.S. is received! The Klingons gel even! 

SPACE TILT (Apple only) Prke: $10.95 Cassette 

S14.95 Diskette 

Use the game paddles lo till the plane of the TV screen to "roll" a ball into a hole in the screen. Sound s'trnpt? Not when 
the hole gels smaller and smaller! A built-in timer allows you lo measure your skill against others in this habit-rorming ac- 

GAMES PACK I and GAMES PACK II Price: S 9.95 each, Cassette 

$13.95 each. Diskette 
GAMES PACK 1 contains BLACKJACK. LUNAR LANDER, CRAPS, HORSERACE. SWITCH and more. GAMES 
PACK II includes CRAZY EIGHTS. JOTTO. ACEY-DUCEY. LIFE, WUMPUS and others. Available for all corn- 



Why pay 15.95 or more per program when yoi 

STUD POKER (ATARI only) 



a DYNACOMP collection for just S9.95? 



I IV 



Price: Sll.95Cassetle 

S15.95 Diskette 

the classic gambler's card game. The computer deals the cards one al a lime and you (and the computer) bet on 
>u see. The computer does not cheat and usually bcls the odds. However, it sometimes bluffs! Also included is a 
d draw poker betting practice program. This package will run on a 16K ATARI. Color, graphics, sound. 



NOMINOES JIGSAW (TRS-80 only) Prices S16.95 Cassette 

SZ0.95 Diskette 
NOMINOES JIGSAW is an intriguing and sophisticated graphical puzzle. The jigsaw consists of a 9 by 9 board partially 
tilled with randomly chosen shapes (nominocs), of which there are 60 types. By knowing lhal the shapes must be legally 
connected, and by guessing thcshapeal each location, all the nominocs maybe eventually deduced. Scoring is based on 
the number of guesses required and the difficulty of the board set-up. 

MOVING MAZE (Apple only) Price: S10.95Cassette 

S14.95 Diskette 

MOVING MAZE employs the games paddles to direct a puck from one side of a maze I o the other. However, the maze is 
dynamically (and randomly) built and is continually being modified. The objective is to cross the maze without touching 
(or being hit by) a wall. Scoring is by an elapsed lime indicator, and three levels of play are provided. 



BLACK HOLE (Apple only) 

This is an exciting graphical simulation of the probli 



Price: S14.95 Cassette 
S18.95 Diskette 

ed in closely observing a black hole with a space probe. The 

he anomaly lhal ihe lidal stress destroys ihe probe. Control or the craft is realistically simulated using side 
and main ihruslers for acceleration. This program employs Hi-Res graphics and is educational as well as 



challenging. 

TEACHER'S PET I (Available for all computers) 

This is the first of DYNACOMP's educational packages. Primal 
provides ihe young student with counting practice, letter-word 



Price: S 9.95 Cassette 
513.95 Diskette 

intended for pre-school lo grade 3. TEACHER'S PET 
lognilion and three levels of math skill e: 



CRYSTALSIATARl only) 

are built. No iwo patterns are ihe same, and 
has been used in local stores lo demonslral 



PrlcetS 9.95 Cassette 
S13.95 Diskette 

ing, graphics displays accompany with tones which vary as the patterns 
ombined effect of the sound and graphics are mesmerizing. CRYSTALS 






r feaiu 



of ihe 



POKER PARTY (Available for all computers) 



Price: 517.95 Cassette 
$21.95 Diskette 

POKER PARTY is a draw poker simulation based on ihe book, POKER, by Oswald Jacoby. This is the mosl comprehen- 
sive version available Tor micro compulcrs. The party consists of yourself and six other {computer) players. Each of these 
players (you will gel lo know them I has a different personality in ihe form of a varying propensity to bluff or hold under 
pressure. Practice with POKER PARTY before going lo thai expensive game lonite! 



Availability 



DYNACOMP soFlwarc is supplied with complete documentation containing clear explanations and examples. All programs 
will run within I6K program memory space (ATARI requires 24K). Except where noted, programs are available on ATARI. 
PET, TRS-80 (Level II) and Apple (Applesoft) cassette and diskette as well as North Slar single density (double density com- 
patible) diskette. Additionally, mosl programs can be obtained on standard (IBM formal) 8" CP/M Doppydisks for systems 
running under MBASIC. 



' ATARI, PET, APPLE II, TRS-8Q. NORTH STAR, CP/M and IBM are registered trade n. 



tnd/or trademarks. 



BUSINESS, UTILITIES and MISCELLANEOUS 

MAILLISTII (North Staronly) Prlcc:S21.95 

This many-featured program now includes full alphabetic and zip code sorting as well as File merging. Enlries can be 
retrieved by user defined code, client name or Zip Code. The printout fo nal allows the use of standard size address 
labels. Each diskette can store more lhan 1100 entries (single density: over 2200 with double density systems!? 



TEXT EDITOR I (Letter Writer) 

An easy lo use, line-Oliemed text edilot 
editor is ideally suiled for composing le 



Prke: S14.95 Cassette 
518.95 Diskette 

which provides variable line widths and simple paragraph indexing. This ted 
lers and is quite capable of handling much larger jobs. Available for all com- 



PERSONAL FINANCE SYSTEM (ATARI only) Prke: 534.95 Diskette 

PFS is a single disk menu oriented system composed of 10 programs designed to organ ue and simplify your personal 
finances. Features include a 300 transaction capacity; fasl access; 26 optional user codes; dala retrieval by month, code or 
payee; optional printing of reports', checkbook balancing; bar graph plotting and more. Also provides on the diskette is 
ATARI DOS 2. 

F1NDIT (North Star only) Prke:S19.95 

This is a three-in-one program which maintains information accessible by keywords of three types: Personal (eg: lasl 
name). Commercial (eg: plumbers) and Reference (eg: magazine articles, record albums, etc). In addition lo keyword 
searches, ihere are birthday, anniversary and appo uilment searches for ihe personal records and appointment searches for 
the commercial records. Reference records are accessed by a single keyword or by cross-referencing iwo or three 

DF1LE (North Slar only) Prke: $19.95 

"1 his handy program allows North Star users lo maintain a specialized data base of all Tiles and programs in the stack of 
disks which invariably accumulates. DF1LE is easy lo set up and use. It will organize your disks to provide efficient 
locating of the desired file or program. 

COMPARE (North Star only) price: S12.95 

COMPARE is a single disk utility software package which compares two BASIC programs and d tplays the file sizes of 
the programs in bytes, the lengths in lerms of ihe number of statement lines, and the line numbers at which various listed 
differences occur. COMPARE permits ihe user lo examine versions of his software to verify which are the more current, 
and to clearly identify the changes made during development. 



COMPRESS (North Star only) 

COMPRESS is a single-disk utility program which rente 
from North Slar BASIC programs. The source file is pro 



Price! $12.93 

:csand (optionally) REM 
:d one line al a time, ihus permitting very large progra 
Bry, Tile compressions of 20-50*. are commonly achii 



GRAF1X (TRS-80 only) 

This unique program allow 



Price: S12.95 Cassette 
51*5.95 Diskette 

asily create graphics directly from the keyboard. You "draw" your figure using the 
program's extensive cursor controls. Once ihe figure is made, il is automatically appended lo your BASIC program as a 
siring variable. Draw a "happy race", call il HI and ihen print il from your program using PRINT HI! This is a very easy 

TIDY (TRS-80 only) Prke: S10.95 Cassette 

S14.95 Diskette 
TIDY is an assembly language program which allows you to renumber the lines in your BASIC programs. TIDY also 
removes unnecessary spaces and REMark statements. The rcsull is a compacted BASIC program which uses much less 
mcmoiy space and executes significantly faster. Once loaded. TIDY remains in memory; you may toad any number of 
BASIC programs wiihoul having to reload TIDY! 

NORTHSTAR SOFTWARE EXCHANGE (NSSE) LIBRARY PrkeS9.95 Diskette 

DYNACOMP now distributes the >u+ volume NSSE library. Most of these diskettes ofTer an outstanding value for the 
purchase price. Write for details regarding ihe contents of ihis library and quantity (four or more) purchases. 



STATISTICS and ENGINEERING 

DATA SMOOTHER (Not available for ATARI) 

This special dala smoothing program may be used lo rapidly derive useful information fior 
ingdata which are equally spaced. The software features choice in degree and range of Til, 
second derivative calculation. Also included isaulomatic plotting of Ihe inpul data and si 

FOURIER ANALYZER (Available for all computers) 



■other 



Price: S14.95 Cassette 
518.95 Diskette 

ihe frequency spectra of limited duration signals. The program features automatic scaling 
and results. Practical applications include the analysis of complicated patterns in such fields 



TFA (Transfer Function Analyzer) 

and Filters by examining their response lo pulsed inputs. TFA is a maj 
contains an engineering-oriented decibel vetsus log-frequency plot as * 
ANALYZER is designed for educational and scientific use. TFA is an 

HARMONIC ANALYZER (Available for all computers) 



Prke: S19.95 Cassette 
S23.95 Diskette 

ions of systems such as hi-fi amplifiers 
ilion of FOURIER ANALYZER and 
editing features. Whereas FOURIER 
g tool. Available for all compulcrs. 



Price: 524.95 Cassette 
S28.9S Diskette 

HARMONIC ANALYZER was designed for the spectrum analysis of repetitive waveforms. Features include dala file 
generation, edilingand storage/retrieval as well as data and spectrum plotting. One particularly unique facility is that ihe 
inpul dala need not be equally spaced or in order. The original data is sorted and a cubic spline interpolation is used to 
create the dala file required by the FFT algorithm. 

FOURIER ANALYZER, TFA and HARMONIC ANALZYER may be pruchased together for a combined price of 
144.95 (three cassettes) and $36.95 (three diskettes). 

Prke: 519.95 Cassette 
SZ3.95 Diskette 
versatile one-dimensional least squares "polynomial" curve filling pro ■ 
utomatic degree determination option; an extensive internal library of fit- 
I curve plotting; a statistical analysis (eg: standard deviation, correlation 
icw fits may be tried without reentering the data. REGRESSION I is cer- 
. lysis software library. 



REGRESSION I (Available for aU computers) 



-yhigha 



optionally 



REGRESSION I is 
gram. Features inch 
ling functions; dala editing; 
coefficient, etc.) and much n 
la'inly ihecornersloneprogr, 

REGRESSION II (PARAFIT) (Available for all computers) 



polynomial filling, and PARAFIT Tor iht 

REGRESSION 1 and 11 may be purchased together for £36.95 (< 



Prke: S19.95 Cassette 
523.95 Diskette 

s in which (he parameters are imbedded (possibly nonlineaily) in the fitting 
inalform. including the parameters (A(l). A(2). etc.) as one or more BASIC 
lanipulated and plotted as with REGRESSION I. Use REGRESSION I for 
c complicated functions. 

;)and $44.91 (diskettes) 



BASIC SCIENTIFIC SUBROUTINES, Volume I (Not available for ATARI) 

DYNACOMP is lhc exclusive distributor for ihe software keyed to the text BASIC Scientific Subroutines. Volume /by F. 
Ruckdeschel (see lhc BYTE/McGraw-Hill advertisement in BYTE magazine, January 1981). These subroutines have been 
assembled according lo chapter. Included with each collection is a menu program which selects and demonstrates each 

Collection l\: Chapters 2 and 3: Dala and function plotting, complex variables 
Collection #2 Chapter 4: Matrix and veclor operations 

Collection Ki: Chapters 5 and 6; Random number generators, series approximations 
Price per collection: 114.95 Casselle 
JI8.95 Diskette 
All three collections are available Tor $19.95 (three cassettes) and $49.95 (ihree diskettes). 

Because ihe lexl is a vital pan of ihe documentation, BASIC Scientific Subroutines. Volume I is available from 
DYNACOMP for 119.95 plus 75; postage and handling. 



Circle 173 on inquiry card. 



Ordering Information 



All orders are processed and shipped postpaid within 48 hours. Please enclose 
mation. If paying by VISA 01 Master Card, include all numbers on card. For t 
p~u.ga.nd handling. 

Add 12.50 10 diskette price Tor 8" floppy disk (IBM formal soft sectored, CP/M, Microsoft BASIC) 
•TRS-80 diskettes arc nol supplied with DOS or BASIC. 

Deduct 10% when ordering 3 or more programs. 

ler. Write for detailed descriptions of these and other program 



DYNACOMP, Inc. 

6 Rippingale Road 

Pittsford, New York 14534 

(716) 586-7579 

New York State reildcnli pleu, idd 7 » NYS ,,le, IM 



Circle 174 on Inquiry card. 



r 



AT LAST! 



Mass production prices (or high quality software. Buy direct and save 50%. Also 
available tor CPM and HDOS. 

DATA BASE MANAGER Mod I & III S69. S149 (48K), Mod II S199 

Maintain a data base and produce reports, all without user programming. Define 
tile parameters and report formats on-line. Key random access, fast multi-key 
sort, field arithmetics, audit log, label. No time-consuming overlays. 500 happy 
user-s in one year. Mod-ll and 48K versions have over50enhancements. including 
40 fields maximum. IDM-M2 is great!' - 80-US. 

A/R Mod-IS69 Mod-ll S149 Mod-Ill S69 

Handles invoices, statements, aging, sales analysis, credit checking, forms input, 
and order entry. Unlike other accounts receivable programs, ours can be used by 
doctors, store managers, etc. 

WORD PROCESSOR S49 

Centers, justifies, indents, and numbers pages. Mod-I version features 
upper /lower case without hardware modification! File merge option available. 

MAILING LIST Mod I & III S59, S79 (48K). Mod-ll S99 

The best 1 Compare and be selective. Includes forms input. 5-digit selection code, 
zip code extension, sort on any field, and multiple labels. Who else offers a report 
writer and merges with word processor? 

INVENTORY Mod I & III S89, S109 (48K) Mod-ll S149 

Fast key random access. Reports include order info, performance summary, EOQ 
and user-specified reports Many people have converted to our system! Next to 
impossible to damage the file.'' 

GL. A/R. A/P. PAYROLL Mod-ll S129 each 

Integrated accounting package 100* page manual As opposed to Osborne's slow 
binary search and 64 column screen, we use fast ISAM and 80 columns. Dual disk 
and TRSDOS required. 

L21B S59 

A cassette package of 10 business programs for Level I1 16 K systems. Includes 
word processor and data base manager. Poker game S19. 

Most programs are on-line, interactive, random-access, bug-free, documented, 
and delivered on disks. Mod-I programs require32K TRSDOS. Were »1 in business 
software— don't let our low price fool you! Ask for our free 20-page catalog if 
you're still not convinced. Compiled versions are available. 



fc* 



MICRO ARCHITECT. INC. 

96 Dothan St., Arlington, MA 02174 



interactive video 

• Provide a sophisticated teaching/training 
system or an audiovisual procedure manual 

• Offer a comprehensive audio-visual data- 
base searchable by keyword 

• Integrate interactive power of the 
computer with audiovisual impact of 
videotape using the same TV screen 

• Use with Apple* or RS-232 computers, 
Sony or Panasonic VCR's 

• Order in Applesoft or PASCAL, Choice of 
Authoring systems. Frame accurate stops 
and switches, no accumulated error 



Cavil 



SYSTEMS, INC. 

26 Trumbull Street, New Haven, CT 06511 
(203) 562-4979 



*TM - Apple Computer Co. 



B2/81 



power even while they are not in motion). The solution 
required removing the motor-driver transistors from the 
main circuit board and adding a piggyback board at the 
motor. 

The new circuit uses three 7486 two-input exclusive- 
OR gates and a flip-flop to determine whether the circuit 
is in the step or the hold mode. A diode and a pass tran- 
sistor are added to determine whether 12 V or 35 V DC 
will be applied to the motor windings. The rest of the cir- 
cuit is similar to the original, except for the addition of 
another set of inverter /drivers, which are necessary 
because the wiring to the motor-winding pairs has been 
reversed. In the hold mode, the diode feeds 12 V to the 
motor windings, enabling them to hold the feed 
mechanism at the current line. When a step signal arrives 
from the processor, the transistor is turned on (by the 
exclusive-OR gates and the flip-flop) and applies 35 V to 
the motor. In this way, the higher voltage is available for 
stepping, when maximum torque is needed. The rest of 
the time, the motor sees only 12 V, and its average 
power-dissipation limit is never exceeded. 

Once again, Heath assures that this tactic, which 
coaxes superior performance from a conventional part, 
will not appreciably shorten its life. Thumb-and-index- 
finger measurement confirms that the motor does not 
become appreciably hotter with the new driver than it did 
with the original one. Apparently, burning the candle at 
both ends works in this instance. 

Configuring the H-14 

When the printer has been assembled and tested, it is 
time to connect it to a computer and do some printing. As 
with most interfacing tasks, this one requires some plan- 
ning. Heath chose to include a 256-character buffer in the 
H-14 so that, for example, a multitasking system could 
fill the buffer and go off to continue other tasks. To 
facilitate this kind of operation, the H-14 can accept serial 
ASCII (American Standard Code for Information Inter- 
change) data at up to 4800 bps (110 to 4800 bps options 
are selected at a switch in the printer). Handshaking be- 
tween the printer and the computer system can take place 
in either of two ways. When the buffer is empty, the H-14 
sends an ASCII Control-Q (hexadecimal 11) on the return 
communication line to its host. When the buffer is full, a 
Control-S (hexadecimal 13) is transmitted. The computer 
software can therefore use these characters as signals to 
start or stop sending data. 

The other handshaking option includes having the 
computer system look at the RTS (Request To Send) line 
from the printer. When the line buffer is empty, RTS is 
on (low), indicating that there is room for sixteen more 
characters; when it is full, RTS goes off. 

I have already mentioned that the H-14 can provide 
variable line widths and line spacings. The 80-column 
and 132-column options can be selected by means of a 
push-button on the front panel. These and all the other 
options can also be obtained through software com- 
mands transmitted in the text. The sequence Escape/u/ 
Control-T, for example, switches the output from 
80-column to 96-column format; an Escape/y sets the line 
spacing to 8; the Form Feed (hexadecimal OC) executes a 
carriage return and a form feed. The front panel also has 
Feed Forward and Feed Reverse buttons which can be 
used to position the print head at the top of a form, when 
the printer is switched off-line. 

One option which will probably not be offered for the 



258 February 1981 © BYTE Publications Ire 



Circle 175 on Inquiry card. 



THE PERFECT MARRIAGE 



CHRISLIN 256KB MEMORY 




minim i/i/i 





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DEC® LSI® 11/23 



NOW AVAILABLE! 256KB memory on a dual height board only $1 925. CHRISLIN INDUSTRIES 
now offers state-of-the-art 64K RAM Memory system designs. Like our recently introduced 
512KB MULTIBUS® compatible single card memory our 256KB LSI 11/23 memory is an 
industry first. 

Free up critical and expensive backplane space. Saves you 3 dual slots. 

Addressable in 4K increments up to 4 Megabytes. 

On board parity generator checker totally DEC hardware and software compatible. 

Single 5 volt power requirement. 

Battery back-up capability. 256KB unit draws less than 300 ma at 5 volts in battery back-up 
mode. 

Tested and burned in. Full year warranty. 



DON'T ASK WHY WE CHARGE SO LITTLE, ASK WHY THEY CHARGE SO MUCH. 



« 



Chrislin Industries, Inc. 

Computer Products Division 
31352 Via Colinas • Westlake Village, CA 91362 • 213-991-2254 



Multibus is a trademark ohne Intel Corp t SI II is a trademark ol Digital Equipment Corp 



Circle 176 on inquiry card. 



BYTE February 1981 259 



H-14 is an F8 processor with different programming to 
permit graphics printing. The reason is the lack of pro- 
gram and table space in the processor. Another con- 
sideration is that the paper movement is not reversible 
because of the H-14's rear paper inlet. One is tempted to 
try to feed the paper through the ventilation slot in the 
bottom plate of the enclosure — it is in just the right posi- 
tion below the print head and platen. An LED and photo- 
diode are mounted in the normal feed path, however, to 
detect the out-of-paper condition. If the paper were 
brought in through the bottom of the cabinet, modifica- 
tions to a paper guide would have to be made and the 
paper-detector feature would have to be sacrificed. 

The Results 

The print output of the H-14 is pleasing to the eye and 
easy to read, even when the 132-column format is used. 
The ribbon is canted a few degrees to minimize ink drain- 
ing caused by the print head's covering the same area of 
the ribbon in repeated passes across the page. The ribbon 
can be canted further by shifting washers under its 
pulley. This gives additional protection from draining. 

The spacing between the tractor-feed gears is ad- 
justable, so that they can accept papers from 5.5 to 
24.5 cm (2V2 to 9V2 inches) wide. Although I normally 
use 24.5 cm (9V2-inch) forms which can be burst to a 
22 cm (8V2-inch) page, I have also used 22 cm multiform 
paper and 8 cm (3V2-inch) wide label forms. The H-14 
handles the heavy labels very well, and it easily pulls 
20-pound paper from a box on the floor, two feet below 
the feed inlet. 




CURE TO 

SOFTWARE 

PROBLEMS 



PROFESSIONAL SOFTWARE 

Medical, Dental & Legal Systems, 
Accounting & Financial, Educational, 
Word Processing, Office Management 

Check your Local Dealer or Contact: 

Chofle/ fllonn & A//ociote/ 

7594 San Remo Trail 

Yucca Valley, Ca. 92284 

(714) 365-9718 



Apple II 



TRS-80 



Tl 99/4 



Is the H-14 the All-American Printer? 

A number of new, inexpensive impact printers have 
entered the market since the H-14 was first advertised in 
January 1979. IDS, C Itoh, and Anadex are a few of the 
companies which have produced under-$1000 offerings 
with a variety of features. A buyer faced with the task of 
choosing among them will do well to check the perfor- 
mance specifications very closely. The H-14's need for 
cool-down time after printing ten or fifteen pages could 
be annoying in an office environment. On the other 
hand, some of the units that can print continuously may 
have no thermal overload protection and rely on the of- 
fice air conditioning to keep things cool. Others have 
long duty cycles, but do not offer variable page and line 
widths. 

The H-14 is a particularly good choice for the personal- 
computer user because it not only performs well, but it 
should be inexpensive to maintain. It accepts a standard 
B-72 Teletype ribbon that can be purchased at most office 
supply stores for two or three dollars. If the kit is 
assembled, the buyer has a working knowledge of the 
construction of the unit and can probably repair 
mechanical faults which might develop. The excellent 
testing and troubleshooting guides included in each of the 
printer's two manuals cover most electrical problems. 

Finally, there are Heath's own service and parts distri- 
bution facilities. Service is available in many cities at 
Heathkit stores, and parts are shipped from the factory 
within 24 hours of a telephone call, if a credit-card 
number is provided. 

Parts are not expensive, by the way. The most expen- 
sive is the print head itself, which costs $133. The next 
dearest (excluding the power transformer) are the paper- 
drive motor and F8 microprocessor, priced at $15.95 and 
$14.90, respectively. Considering that a service contract 
for a commercial printer can cost in excess of $50 per 
month and that a service call to replace an ailing circuit 
board has been known to cost over $125, the H-14 
should, indeed, be very economical to operate, even in 
the unlikely event that a part should fail. 

The H-14 does not quite satisfy my criteria for the All- 
American line printer, but it is certainly an excellent buy 
and, more important, a tough competitor for the title. ■ 



A Public Service of This Magazine & The Advertising Council 

Need help? 
Callus. ■£ 



CjOUKH 



Red Cross 
counting 
on you. 



260 February 1981 © BYTE Publications Inc 



Circle 177 on inquiry card. 



Is BASIC too SLOW? 

OSBORNE/ 
McGraw-Hill's 
Assembly Language 
books help you 
speed up your 
programs 




by Lance 
Leventhal 



by Lance Leventhal 



Assembly language programming is fast and efficient. For 
some applications, like computer animation or close control of 
peripherals, its speed makes it indispensable. 

Now Osborne/McGraw-Hill helps to simplify assembly 
language programming. You needn't know anything about 
assembly language to use our ALP series. Each book is a 
straightforward, self-teaching textbook that is both 
concise and easy to understand. Each book 
explains assembly language programming, 
describes the function of assemblers, 
structured programming, and presents 
over 80 fully debugged practical 
programming examples. 

Table of Contents: 

Introduction to Assembly Language Programming 
Assemblers 

The Assembly Language Instruction Set 
Simple Programs 
Simple Program Loops 
Character Coded Data 
Code Conversion 
Arithmetic Problems 
Tables and Lists 
Subroutines 
Input/Output 
Interrupts 

Problem Definition and 
Program Design 



by Lance Leventhal 
Adam Osborne 
Chuck Collins 



Debugging and Testing 
Documentation and Redesign 
Sample Projects 




by Lance 
Leventhal 



by Lance Leventhal 



h&> 



Name. 



Address. 



City_ 
State. 



.ZIP. 



Phone. 



HOW TO SHIP. 



ef>. 



OSBORNE/McGraw-HIII 
630 Bancroft Way, Dept. B12 
Berkeley, California 947 lO 



m 



', *°ok 


Price 


Qty 


Amount 


':' 6809 Assembly Language Programming 

-^- now available 


Si 6.99 






6502 Assembly Language Programming 


516.99 






ZBO Assembly Language Programming 


516.99 






68OO Assembly Language Programming 


515.99 






S080A/8085 Assembly Language Programming 


515.99 






ZSOOO Assembly Language Programming 


519.99 






The 8O86 Book 


516.99 






To order, return coupon with check or money Tax 
order. Include 75« per Item for 4th class mail, 
SI .25 per book UPS, or S2.50 per book air mail In the U. S. Shipping 






California residents also Include local sales tax. ti-vtai 
To place an order by phone, call: 415/548-2805 TOTAL 





1123 



Circle 178 on inquiry card. 



BYTE February 1981 



261 



Product Review 



Zork, The Great Underground Empire 



Bob Liddil, POB 66, Peterborough NH 03458 



Deep within the inky underground 
Lurk things only half whispered of 
And twisty hidden passages 
Which hide both treasure and death. 
But who can deny the challenge 
Offered to he who would trespass here, 
For would not the lure of gold and glory 
Be worth more to a man than breath? 

From Song of Zork by 
Freerover the Bard 

Adventure has evolved many times during its short 
history. From Crowther's and Wood's creation to the 
genius of Scott Adams to the wild antics of Greg Hassett, 
the journey has been exciting and entertaining for the 
fans of inventive computer puzzles. No single advance in 
the science of Adventure has been as bold and exciting as 
the introduction of Personal Software Inc's Zork, The 
Great Underground Empire. 

The first thing that everyone will look for when Zork 
boots up is the blinking cursor, and the "I AM..." and 
"YOU SEE..." format that Scott Adams has popularized 
in his nine Adventures. That is not the case here. The 
screen layout is arranged in such a way as to move the 



Af a ninnro 


Name 


Language 


Zork, The Great 


Z80 machine code 


Underground Empire 


Computer 




Radio Shack TRS-60 


Type 


Model I with 32 K 


Adventure game 


bytes of memory and 




one disk drive 


Manufacturer 




Personal Software Inc 


Documentation 


1330 Bordeaux Dr 


Printed instructions 


Sunnyvale CA 94086 


included 


(408) 745-7841 






Audience 


Price 

$39.95 


Anyone interested in 


Adventure or fantasy 




gaming 


Format 


Backup Capability 


5-inch floppy disk 


None apparent 



WHERE prompt (which gives your current location in the 
game) down to the bottom of the screen. I found this 
most useful after reading ten or twelve lines of detailed 
area description. Additionally, the number of turns 
elapsed, the number of points accumulated, and the loca- 
tion form an information display on the bottom line of 
the screen. Other game information scrolls upward as the 
game progresses, giving a very professional screen layout 
for the game. 

If you happen not to have an unlimited amount of time 
to spend with your computer, Zork has a SAVE com- 
mand that allows you to save your position in the game 
onto a blank, initialized floppy disk. While some 
cowards use it to retain their hard-earned position in the 
game before making some dangerous move, the true pur- 
pose of this command is to let you follow the game 
through to its ultimate end (which may take weeks), or as 
protection against losing your position due to, say, a 
brief power failure. 

Zork comes on a write-protected single-density 5-inch 
disk with what appears to be its own operating system 
doing the booting and initialization. The disk defied ex- 
amination by the most sophisticated methods available to 
me. I hope that Personal Software (which distributes 
Zork) will be able to foil the software pirates and traders 
for a while. The disk seems to be absolutely uncopyable. 

Loading and preparing for play is simple enough. 
Merely insert the Zork disk into drive and press the 
reset button of your computer. When the program is up 
and running, a pleasant block cursor greets you. You are 
now ready to play Zork. 

Zork requires a 32 K-byte disk system (in this case, a 
Radio Shack TRS-80 Model I with 32 K bytes of memory 
and one disk drive) due to the eloquence of the descrip- 
tions and the large number of locations that are stored on 
the disk to be recalled at the appropriate times during the 
game. The advance copy I used had no instructions, so, 
in the beginning, I played a fairly straight game of 
Adventure. 

I was eager to test Zork's biggest selling point, 
intelligent input (ie: its ability to accept free-form instruc- 
tions). I typed "OPEN THE BAG AND GET THE 
LUNCH," in reference to a brown paper sack inside the 
house. The computer complied. There was water and 
food, so I typed "EAT THE LUNCH AND DRINK THE 
WATER," to which the computer responded with 
gratitude for satisfying its hunger and thirst. 

I was hooked. 



262 Febiuary 1981 © BYTE Publications Inc 



QMEG A "WHOLESALE COMPUTER PRICES" 
sales DIRECT TO THE PUBLIC 

co - 12 Meeting St., Cumberland, RI 02864 




I lntcrtec Superbrainl 
32K Ram - $2449 
64K Ram • $2649 



PRODUCT SPECIAL 

of the MONTH!! 




NEC spinwritcr 
5510 5530 - $2449 




Apple II- 16K$ 949 
48K$1099 





Diablo 630 
H995 

52195 (with tractor feed) 



Products are 

NOW 

IN 

STOCK 

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Circle 179 on inquiry card. 



BYTE February 1981 



Exploring Zork 

This Adventure begins in a beautiful forest near a large 
white house that is boarded up in an obvious attempt to 
keep explorers out. I managed to get into the house 
through the front once, but I was plunged into darkness 
and eaten by a monster called a grue. The game gave me 
the option of reincarnating myself, which I did (at a cost 
to myself of 10 points). I was revived in a forest. 

Beyond the forest is a deep and beautiful canyon 
through which the River Frigid flows. This was the first 
time I had ever been at the end of the rainbow. No, I 
didn't see a pot of gold, but just because I didn't see it 
doesn't mean it wasn't there. 

In these three locations (ie: house, forest, canyon), the 
descriptions were lavish, sparing no words in their 
bestowal of clues and information to the player. An 
ordinary jeweled treasure, in the form of a bird's egg, 
more than once sent me scurrying to the dictionary in 
search of the meanings of some of the words used to 
describe it. 

There are many tools available to the explorer. I was 
able to obtain a lantern (light wards off grues), a length of 
rope, a nasty-looking knife, an elvish sword (which 
glows for reasons of its own), a refillable water bottle, a 
lunch, and garlic (which presumably repels Were-beings 
or Vampires, though I encountered none). Armed with 
these things, I entered the Underground Empire in search 
of gold and glory. 

There was this pugnacious troll who popped up in the 
middle of a room description early in the game. Here, I 
got a chance to test thescombat capabilities of the game. I 



Desk Main/Frame 



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• 10 SLOT MOTHERBOARD INCLUDES CONNECTORS 

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typed "ATTACK TROLL", to which the computer sup- 
plied a supplemental <with hands > . Look out! 
Remembering that the program accepts more complex in- 
put, and, having survived the first combat turn, I typed 
"ATTACK TROLL WITH SWORD." This gave more 
satisfactory results: the troll expired, his body obligingly 
turning to black smoke in the interest of litter-free 
dungeon delving. 

A thief came along shortly thereafter and challenged 
my right to exist in Zork. I typed "THROW KNIFE". He 
caught it in his sack and dispatched me to the nether- 
world, all in one swift motion. I could still hear him 
laughing as I lay ruefully reincarnated on the forest floor. 
I was ten points lighter and my possessions were scattered 
to the four winds. Sadder but wiser, I reentered the lower 
levels after 20 minutes of rounding up those items that 
were absolutely needed. 

More cautious now, I explored the passages and tun- 
nels of Zork (level 1). There are no unwarranted loca- 
tions here — unless you can count the presence of a dam 
with color-coded control buttons in a maintenance room. 
Gleefully, I began pushing buttons, something I should 
know better than to do, as a veteran of the Death Dread- 
nought and Strange Odyssey Adventures. When the 
water level began rising, I was not concerned. Then I 
drowned. 

The program was really getting testy with me by now. 
Grudgingly I was reincarnated by the Patron Deity who 
guards the souls of all Adventurers. Empty-handed once 
more, I resumed my journey. I retraced my steps to the 
Loud Room, where whatever you say is echoed. Then, 
after 768 turns and an afternoon of unparalleled enjoy- 
ment, my luck ran out. I became Grue Munchies, part of 
the balanced diet of silly dungeon players allotted to 
those carnivorous native dark dwellers of Zork. 

On other occasions, I have been expelled from Zork on 
multiple charges of being a reckless Adventurer. None- 
theless, armed with the dubious rank of Amateur Ex- 
plorer and my knowledge of the highest levels, I am look- 
ing forward to the time when I will plunge once more into 
the troll-, thief-, and grue-laden depths of the Under- 
ground Empire. 

Zork, as peer to the Microsoft Adventure and heir 
apparent to the throngs of Adventure cultists who wait 
breathlessly for each new offering, is equal to the 
awesome task it has been given. That the program is 
entertaining, eloquent, witty, and precisely written is 
almost beside the point. Unlike the kingdoms of the 
Adventures for machines with 16 K bytes of memory and 
far from the classic counter-earthiness of the Colossal 
Cave in the original Adventure, Zork can be felt and 
touched — experienced, if you will — through the care and 
attention to detail the authors have rendered. 

I've been to Zork today. Tomorrow, I will take a 
friend. Together we will unwrap the cloaks of mystery 
surrounding this most excellent and memorable work of 
computerized fiction. And when we have extracted from 
this land every drop of adventuring that can be obtained, 
we will likely not be kept waiting. A sequel is nearing 
completion, even as this is being written. 

Somebody, please, let me know when it's done.H 



264 



February 1981 © BYTE Publications Inc 



Circle 180 on inquiry card. 



COMPUTING POWER FOR THE 80'S 



8Mhz. 



8086 



WITH 



MICROSOFT 



BASIC 



OPENS THE DOOR TO HIGHSPEED 16-BIT COMPUTING 



BASIC-86 



IT'S THE STANDARD — This BASIC is essentially identical to 
version 5 of Microsoft's BASIC interpreter, the accepted standard 
with widely available application programs. Programs distributed in 
CP/M® format are easily converted to the 86-DOS system. (CP/M is 
a registered trademark of Digital Research.) 

IT'S FAST — It is two to seven times faster that BASIC-80 on a 4 
Mhz. Z-80, depending upon application. 



BREAKING THE 64K BARRIER — How many of you can run an 
extended disk BASIC and see the message "63309 Bytes free" 
when it signs on? 

RUNS UNDER 86-DOS — Our high-performance operating system 
can load the 30K BASIC interpreter in less than 2 seconds. 
LOADing and SAVEing BASIC programs is done with similar 
speed. 



8086 HARDWARE 



MEMORY — Our two card 8086 CPU set is the only high- 
performance 16-bit processor for the S-100 bus that allows using 
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speed — in any mix. 

16-BIT OR EXTENDED ADDRESSING — Special circuitry is 
included to allow memories without IEEE extended addressing to 
be used in systems with more than 64K (uses PHANTOM). 



FAST 8 MHZ. OPERATION — Gives you high performance without 
requiring expensive memory. Most any 250 nsec. static memory 
board will do the job. Or, at the flip of a switch, a 4 Mhz. clock may 
be selected and/or a wait state may be added. 

2-CARQ CPU SET — Includes serial I/O, parallel I/O, a monitor in 
2716 EPROM, a time-of-day clock, and a very flexible and 
expandable vectored interrupt system. 



86-DOS m 



THIS HIGH-PERFORMANCE disk operating system provides a 
hardware-independent environment for running programs. By pre- 
senting a high-level interface for disk and peripheral I/O, the 
operating system relieves a considerable burden from the program. 

DEVELOPMENT SOFTWARE — 86-DOS provides a complete 
package of development software, including editor, assembler, 



debugger, Z80 to 8086 source code translator, and utilities 



I/O CONFIGURATION — The hardware-dependent portions of the 
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hardware configuration. 



From Seattle Computer, the System Design Experts 



The products described here are only the beginning of a 
broad line of high-performance hardware and software 
products for the 80's. All of it is designed with "The Big 
Picture" — the total system — in mind. 

For highest reliability, all of our hardware uses bus 
receivers which exceed the IEEE specifications by including 



hysteresis. The system already includes complete hardware 
support for the multi-user superset of 86-DOS that will be 
released later this year. And our future products, such as a 
high-speed DMA controller for floppy and hard disks, will 
demonstrate an even further support for fast multi-user 
systems. 



Prices: 8 Mhz. 2-card CPU set, fully assembled, tested, guaran- 
teed, documented, 86-DOS included — $595; BASIC-86 — $350. 
Sale price ot $280 for 8/1 6 1 6-bit RAM ends March 1 . Manuals for all 
SCP products may also be purchased separately. Overseas orders 
must be prepaid in US funds and include $10 per board for air 
shipment. 

Circle 181 on inquiry card. 






i Seattle Computer Products, Inc. 

^ f ^ 1 1 14 Industry Drive, Seattle, WA. 98188 

(206) 575-1830 

BYTE February 1981 265 



Programming Quickies 



Energy-Saving 
Cost /Benefit Analysis 



Richard Hetherington 

637 Pendleton Ave, Apt D 

Chicopee MA 01020 



The recent skyrocketing cost of energy makes us think 
of ways of conserving heat and saving money, whether 
by increased home insulation, using storm windows, 
lowering the thermostat, or any number of other 
methods. Cost versus benefit is always debated. How 
many times have you asked yourself: will the cost of 
adding 6 inches of insulation to the attic far outweigh the 
benefits? 

In order to answer the cost/benefit question relating to 
home insulation, the mechanism of heat travel must be 
understood. I will briefly review the concepts of heat 
transfer, what influences it, and show how to use a 
BASIC program to make the cost/benefit decision. 

Heat Transfer 

Heat can travel between locations by any of three 
mechanisms: conduction, convection, or radiation. 

Conduction is the flow of heat by molecular vibration 
and is usually associated with transfer through solids. For 
example, when a spoon is placed in a cup of hot coffee, 
the spoon gets hot by conduction of heat from the liquid. 

Convection is the transport of heat through a fluid 
transporting medium by fluid movement caused by dif- 
ferences in density due to different temperatures, as when 
air picks up heat from a radiator in the home and 
distributes it throughout a room. 

Radiation transports heat through electromagnetic 
energy, which is absorbed and converted to heat energy 
by a solid material. For instance, if you stand close to a 
blazing fireplace the radiant heat can become unbearable. 

Heat can be lost from your home by all three mechan- 
isms, but in most cases, the loss by conduction is most 
significant and is our main consideration. 

The flow of heat from one place to another by steady- 
state conduction can be expressed by: 

Q = TxA/R 

where: Q = heat flow in BTU (British thermal 

units) /hour 
T = temperature difference in °F (degrees 



Fahrenheit) 

A = area of heat flow in square feet 
R = resistance to heat flow in 
hour-square-feet- °F/BTU 

The resistance to heat flow is related to the thickness of 
the material through which the heat is flowing, and the 
thermal conductivity (shown in table 1) of the material. 
For flat surfaces, it is found by: 

R = L/K 

where: L = thickness of material in inches 

K = thermal conductivity of the material 
in BTU-inches/hour-square-feet-°F 

If the heat is traveling through more than one material 
then R is expressed as: 

R = U/K, + L 2 /K 2 + L3/K3 + ... 

where: L l( L 2 , L 3 ... = the thickness of each 

material through which the heat flows 
Ki, K 2 , K 3 ... = the thermal conductivity 
of each material 

The R value can be calculated for any number of 
materials sandwiched together as long as the thickness 
and thermal conductivity of each material is known. 

Looking at the formulas, you can see that the flow of 
heat depends on the temperature difference, the area it 
flows over, and the thickness and thermal conductivity of 
the material it flows through. Using these three formulas, 
you can readily calculate heat loss by conduction through 
flat surfaces. 

Once the rate of heat loss is known, its cost can be 
calculated. Table 2 lists common fuels, the heating value 
of the fuel, and approximate cost of that fuel. The cost of 
the fuels will vary significantly depending on your loca- 
tion and the quantity purchased. For maximum accuracy, 
modify the fuel costs in table 2 to match the particulars of 
where you live. 



266 February 1981 © BYTE Publications Inc 




computer 
products, inc. 



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MODEL #CX853 16K RAM MODULE 

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Optional Z-flO monitor program — 
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LEEDEX 100, 12" B&W $129.00 

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Circle 182 on inquiry card. 



BYTE February 1981 267 



Circle 183 on inquiry card. 



MAIL ORDER DISCOUNTS 



"apple computer 

Sales and Service 




APPLE II PLUS 48K 

$999 



APPLE #// CALL FOR PRICES 

ACCESSORIES 




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M&RSURR-MOD RF MODULATOR 30 

CENTRONICS PRINTER INTERFACE CARD . .179 

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LEEDEX VIDEO 100 12" B8.W MONITOR 139 



290 



MIC ROSOFT 2-80 SOFTCARO SYSTEM 
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LANGUAGE SYSTEM W/PASCAL 395 

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SOFTWARE 



APPLE FORTRAN 159 

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APPLEPLOT GRAPH & PLOT SYSTEM 60 

CCA DATA MANAGEMENT 85 



515 



THE CONTROLLER BUSINESS SYSTEM 

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computer age. inc. 

Authorized Apple Dealer & Service Center 
4688 CONVOY ST., SUITE 105, SAN DIEGO, CA 92111 (714) 565-4042 




-•" Clock/Calendar 

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Now available on Three Buses 

Features *APPLEII 

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• Simple to Program, 

S I 50 FOB ' Apple is a Trademark of 

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Dealer Inquire (714) 536-5000 

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Programming Quickies 








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240.00 


masonite 




0.33 


macerated paper fill 




0.28 


mineral wool 




0.27 


paper 




0.90 


plaster 




4.00 


plywood 




0.79 


polyurethane foam 




0.20 


slate 




10.30 


snow 




3.24 


sawdust 




0.41 


styrofoam 




0.31 


water 




4.30 


window glass 




5.00 


white pine 




1.04 


wood shingles 




1.15 


Table 1: Thermal conductiv 


ity (K) of common materials used 


in construction and insulation. Note 


that the K for air is 


relatively constant for Vt-inch to 4-inc 


h thicknesses. When 


entering these values into 


the BASIC 


program shown in 


listing 1, use the indicated figures for air (1.0 or 1.2) 


regardless of the thickness 


of the air 


layer. (Data is from 


various sources researched 


by the auth 


or.) 



Fuel 

L P gas 
hardwood 
electricity 
anthracite coal 
natural gas 
#2 fuel oil 
kerosene 



Heating Value (H) Cost (Z) 



21 ,000 BTU/lb 
21,000,000 BTU/cord 
3413 BTU/kW hr 
12,700 BTU/lb 
1050 BTU/cu ft 
138,700 BTU/gal 
135,500 BTU/gal 



$0.245/lb 

$100.00/cord 

$0.055/kW hr 

$0.04745/lb 

$0.004845/cu ft 

$0.93/gal 

$0.97/gal 



Table 2: The heating value in BTUs (British thermal units) 
and cost of various fuels commonly used for home heating. 
The indicated costs are local spot prices in western 
Massachusetts during the winter of 1979-80 and will vary 
significantly in different areas. For the greatest accuracy 
when using the BASIC program shown in listing 1, make sure 
the fuel costs are accurate for your area. (Data is from 
various sources researched by the author.) 



The cost of heat lost is calculated by: 

C = ZXQ/H 

where: C = cost of heat lost in dollars/hour 

Z = fuel cost in dollars/unit 
H = heating value of fuel in BTU/unit 
Q = heat flow in BTU/hour 



268 February 1981 © BYTE Publications Inc 



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